If the sudden resignation of Instagram co-founders Kevin Systrom and Mike Krieger wasn’t enough to make it a tense and taxing week at Facebook headquarters, a new Forbes interview with WhatsApp co-founder Brian Acton isn’t going to help matters much. In the interview, Acton was critical of Facebook’s monetization strategy for the app he and Jan Koum sold to the company for $16 billion. He also seemed to voice a sense of self-guilt for ever being part of the deal that made him extremely wealthy, saying “I sold my users’ privacy to a larger benefit. I made a choice and a compromise. And I live with that every day.” Acton exited Facebook a year before his final batch of stock options vested, a decision that ultimately cost him north of $800 million.

The interview has prompted one of Facebook’s high-level executives, David Marcus, to publicly respond. Marcus led Facebook’s Messenger division for years before switching his focus to the company’s blockchain-related efforts. In a post titled “The other side of the story,” he said that the Forbes interview “contained statements, and recollection of events that differ greatly from the reality I witnessed first-hand.”

Marcus says Zuckerberg gave the WhatsApp founders special treatment

According to Marcus, Zuckerberg went to bat for WhatsApp and its founders numerous times. “WhatsApp founders requested a completely different office layout when their team moved on campus,” he wrote, saying that those asks included “much larger desks and personal space, a policy of not speaking out loud in the space, and conference rooms made unavailable to fellow Facebookers nearby. This irritated people at Facebook, but Mark personally supported and defended it.”

After being convinced by Koum of its vital importance, Zuckerberg became resolute in supporting and defending WhatsApp’s encryption, says Marcus. “From that point on, it was never questioned.” Zuckerberg believed “WhatsApp was a private messaging app, and encryption helped ensure that people’s messages were truly private.” The Forbes piece mentions that managers at Facebook “did question and ‘probe’ ways to offer businesses analytical insights on WhatsApp users in an encrypted environment.”

Marcus also accuses Acton of “slow-playing” the implementation of a feature that would let businesses message WhatsApp users and ultimately help with monetization. “If you have internal questions about it, then work hard to prove that your approach has legs and demonstrate the value. Don’t be passive-aggressive about it,” he added. (In the interview, Acton said he never agreed with Facebook’s plans for targeted advertising in WhatsApp. “They are businesspeople, they are good businesspeople. They just represent a set of business practices, principles and ethics, and policies that I don’t necessarily agree with,” he said.)

Marcus clearly isn’t happy about Acton’s negative painting of Facebook

But Facebook’s blockchain boss saved his harshest words for the end, tearing into Acton for the negative sentiment toward the company. “I find attacking the people and company that made you a billionaire, and went to an unprecedented extent to shield and accommodate you for years, low-class. It’s actually a whole new standard of low-class.” To close, there’s this heap of praise about how great Facebook is:

Facebook is truly the only company that’s singularly about people. Not about selling devices. Not about delivering goods with less friction. Not about entertaining you. Not about helping you find information. Just about people. It makes it hard sometimes because people don’t always behave in predictable ways (algorithms do), but it’s so worth it. Because connecting people is a noble mission, and the bad is far outweighed by the good.

Marcus notes that no one at Facebook asked him to author the defense of Zuckerberg and his company. “I just had to do it. And these are my personal views exclusively.”