First things first: I don't hate octogenarians. I don't have a vendetta against anyone over 80 who likes to begrudgingly give evidence to parliamentary committees. Nor am I in the habit of attacking media moguls on international television. Yesterday was, hopefully, a one off.

If you're of sound mind, you might quite reasonably ask what possessed me to smuggle a shaving-foam pie into Portcullis House and throw it at (though, alas, not into) the face of one of the world's richest and most powerful men. I didn't do it because I wanted more Twitter followers. Simply put, I did it for all the people who couldn't.

It's not difficult to find reasons to dislike Rupert Murdoch. His reach is one of the most insidious and toxic forces in global politics today. The phone-hacking scandal, despicable though it is, barely scratches the surface of the damage done by News International. It is a media empire built on deceit and bile, that trades vitriol for debate and thinks nothing of greasing the wheels of power until they turn in its favour. What's more, no matter what the grievances he wreaks on those he has never met, his power and money keep him forever safely out of their reach.

Yes it's true that Murdoch's power is waning. But it's also true that he will never face real justice. Yesterday's select committee hearing was a farce before the foam ever left my fingers: a toothless panel confronting men too slippery to be caught between their gums.

I was filled with hope as Tom Watson questioned Murdoch Sr relentlessly with the passion and vigour we might expect to be the norm when our elected representatives face down the perpetrators of a modern Watergate. For a few bright moments I thought I might see justice done, keep the pie in my bag and spare myself a night in jail. Those moments were short lived: as committee member after committee member feebly prodded around the issues and Murdoch Jr began to dominate, I knew I was going to have to make a massive tit of myself.

To be honest, I had not expected to get so far, but parliamentary security, with its machine-gun toting cops and scatter X-rays, is apparently no match for a man with some shaving-foam covered plates in his bag. Then, once inside the committee room, I was helped along by some unwelcome luck. I had always intended to wait until the end of the hearings anyway before I launched my circus crusade, and as the penultimate speaker finished several people made their way out, leaving me a clear path to Murdoch. It was a horrible feeling: I had a plan, a pie and no excuses left.

I had intended to unleash a wave of polemic as I made my move. As it turned out, the whole thing was far too weird for me to string two thoughts together, particularly as Murdoch's wife rose from the chair to prevent and avenge her husband's humiliation. As it went, I'm glad I was even able to make the accurate understatement that he was a "naughty billionaire".

As I languished predictably in a prison cell later that evening, I contemplated whether people would understand why I'd done it. I knew it was a tall order: a surreal act aimed at exposing a surreal process was never going to be an easy sell. I worried, too, that my clowning would detract from the scandal, or provide sympathy for Murdoch.

Believe it or not, I even worried about Rupert Murdoch's feelings. You see, I really don't hate 80-year-olds and, at the end of the day, Rupert Murdoch is just an old man. Maybe what I was trying to do was remind everyone of that – that he is not all powerful, he's not Sauron or Beelzebub, just a human being, like the rest of us, but one who has got far too big for his boots.

• Jonnie Marbles received no fee for this article