His name is Billy Eisengrein, better known as the third firefighter on the right.

On Sept. 11, 2001, Billy stood amid the wreckage of Ground Zero when he spotted two firefighters. One held in his hand a miracle: a large, unscathed American flag.

Climbing atop the roof of a construction trailer, piled with debris that used to be the World Trade Center, the men — George Johnson (on the left), Daniel McWilliams (center), and William “Billy’’ Eisengrein — proudly hoisted that flag into the air.

The moment was captured, in its poetry, by the shutter of Record photographer Thomas Franklin.

But 12 years later, that moment has been reduced to rubble.

For the picture of the men, victoriously raising the Stars and Stripes in defiance of the terrorists who tried to destroy us, was slammed and slandered by some staffers at the yet-to-open 9/11 Museum.

Creative director Michael Shulan called the snap too “rah rah America.’’ So says a new book, “Battle for Ground Zero.’’

Eventually, the photo was placed in the museum — grouped with two other pictures, its power reduced by America-averse pinheads.

Once again, Billy Eisengrein feels he’s under attack.

“It offends me as an American,’’ he told me. “To downplay and diminish [the picture]. It is bulls–t!

“It’s political correctness and trying to rewrite history. People are not afraid about offending Americans, and people who have a strong belief on what this country was founded on,’’ said Billy, 49, still a firefighter at Rescue 2 in Brooklyn.

“If it was up to me — and you can print this — if he thinks that picture is too rah-rah America, he should move someplace better in this world to live. I’ve had it with political correctness. It’s taking the country down.’’

Well said, Billy.

How far we’ve fallen since 9/11. The case of the savaged picture illustrates how displays of patriotism make some folks uncomfortable. Many in power, in the media, and even those designing museums that co-star terrorists would rather meditate on what America did to make them hate us, rather than what we can do to vanquish our enemies. A compromise over the picture was proposed by curator Jan Ramirez. The flag-waving photo was minimized in favor of three shots, taken at different angles of the scene.

“Shulan didn’t like three photographs more than he liked one, but he went along with it,’’ said the book.

Ramirez seemed determined to include the photo, albeit in its depleted state. “Several images undercut the myth of ‘one iconic moment’ and suggest instead an event from multiple points of view, like the attacks more broadly,’’ she was quoted as saying.

Shulan was more blunt. He told The Post’s Melissa Klein, “My concern, as it always was, is that we not reduce [9/11] down to something that was too simple, and in its simplicity would actually distort the complexity of the event, the meaning of the event.’’

(“How is that complex? Billy retorted. “It’s just three Americans raising the flag on one of the darkest days this country has seen.’’)

The photographer, whose image has raised $10 million for families of 9/11, was mystified.

“I think the picture has been such a positive thing,’’ Franklin said. “For [museum staff] to be divided over it makes me really sad.’’

The museum reacted — distancing itself from creative director Shulan.

“Never was there any doubt that the 9/11 Memorial Museum would include the historically iconic image of those firefighters hoisting an American flag at Ground Zero,’’ spokesman Michael Frazier e-mailed. “While we are an organization that appreciates different views on a range of subjects, an opinion by one staff member, albeit a valued one who contributed his thoughts in the process of creating the exhibition, does not represent the position of the Museum.’’

The book’s author, Elizabeth Greenspan did not dispute the photo-dissing in her book, first reported in The Post. She would only say the pic was not “nearly excluded’’ from the museum exhibit, but would not elaborate on its depleted state. .

I’ve seen the image of the flag-waving firefighters, which evokes the iconic photo of raising the flag on Iwo Jima, on a postage stamp, on T-shirts and even tattoos. (It was snubbed by the perversely politically correct committee that doles out Pulitzer prizes.).

But it continues to spook folks who see displays of American patriotism as maligning other cultures. Madness.

This photo should be the museum’s centerpiece.

When flacks attack

What a pair.

Anthony Weiner’s spokeswoman, Barbara Morgan, made mincemeat of an intern who criticized the turbo-sexter’s mayoral campaign, issuing a graphic critique of her individual body parts.

Among the tamer terms Morgan employed in her rant was “slutbag,’’ a weird one when you consider Carlos Danger’s unsavory carnal appetites. (She later apologized to the gal she maligned, Olivia Nuzzi.)

You might expect Weiner to tell the female-basher to take a hike. Instead, he’s standing by his woman. I guess it makes sense.

Morgan’s fascination with the female form rivals Weiner’s. And it gives rise to questions about respect for women in the Weiner campaign.

There is none.

Weiner’s fall-back position when his marriage gets rocky is to engage in raunchy sexting and phone sex with a new, tattooed woman. One of his top staffers calls a woman an obscene term that begins with “c.’’

These bimbos were made for each other.

Court’s sweet relief

Keep gulping, New Yorkers.

City dwellers have endured bans on the sale of homemade brownies at school bake sales and the mass invasion of Citi Bikes. But an appeals court this week stopped Mayor Bloomberg’s health police from snatching away sugary drinks of more than 16 ounces.

The insane rule would have transformed large sodas sold in restaurants into contraband, but would not have stanched the flow of caloric lattes and milkshakes into our expanding bodies.

The mayor vows to appeal. Again.

I admire Bloomberg’s efforts to keep New Yorkers svelte. But this is not the way to do it.

A welcome blessing

“If someone is gay and he searches for the Lord and has good will, who am I to judge? We shouldn’t marginalize people for this. They must be integrated into society.’’

— Pope Francis stuns reporters aboard a plane returning from Brazil with conciliatory remarks about homosexuals.

Welcome to the 21st century.

I promise it’ll be worth the wait

To my friends, colleagues and frenemies. You, too, Alec Baldwin:

You won’t be hearing from me for a while. I am taking a leave of absence from this newspaper.

I dread missing the daily lunacies of Weiner/Spitzer, a pair of pervs who made coming to work each day feel like a vacation. I’ll miss giving hell to Gwyneth Paltrow and Lindsay Lohan. Most of all, I’ll miss the give-and-take with you, my loyal readers.

But I can’t stay away too long, and I’ll be back in time for the next celebrity meltdown or psycho-sexual crisis to hit this city.

Count on it.