Sacha Baron Cohen's new baby, Brüno, is a shrieking faggot who embodies every prejudice ever thrown at gay people – that we are shallow, callow and perverted. He buys a black baby from Africa – the price? an iPod – to mimic Madonna. He preys on straight men by charging into their tents naked. He penetrates his pygmy boyfriend with massive dildos powered by exercise bikes. Oh, and the staggering success of the film is a stride forward for gay people.

The Brüno-bashing backlash has profoundly missed the point. Baron Cohen – one of the great satirists of our time – is taking a prejudiced position to its logical conclusion, in order to expose its absurdity. It's how satire works. When Jonathan Swift wrote the greatest satire in history – A Modest Proposal, in 1729 – he suggested that the starving Irish were failing to show any initiative. Obviously, he wrote, they should eat their own babies. There were many contemporary readers who took it as another attack on the barbarian Irish hordes.

During the last US presidential race, the impeccably liberal New Yorker magazine published a front-page cartoon showing Barack and Michelle Obama as Islamist terrorists, fist-bumping amidst turbans and machine guns. Some critics shrieked: you are reinforcing the right's demonology! But the New Yorker was obviously exposing it. By taking those myths literally and setting them down on paper, they were saying: this is what you think the Obamas do behind closed doors? Really? Look at it. Now tell me with a straight face that you think it's true.

Baron Cohen is doing the same. The joke isn't on gay people; it's on the bigots who, when confronted with this creation, believe he is real, and typical of gays. Baron Cohen literally risked his life to make the point. He went to some of the most homophobic places on earth – the refugee camps of the Middle East, and the deep south of the US – and behaved as a gargoyle drawn from the subconscious fears of homophobes.

For example, in the middle of a bare-knuckle wrestling ring in Arkansas, he appeared as 'Straight Dave' and incited a drunken mob to chant "My asshole is only for shitting!". Then he started a fake fight – and after some half-hearted grappling, he starts to make out with his rival, while the mob rages and begins throwing bottles and chairs into the ring. Would anybody be surprised if he had been shot?

Of course, some people will simply see the babbling fag and chuckle, but you can't judge a satire by the reactions of the stupidest members of the audience. If you did, every satire ever written would die a cot-death. Many more will be subliminally shocked to see people take the caricature as real and ask: "would I have done that? What's wrong with my assumptions?"

It's a shame that some gay organisations are focusing their fire on Brüno, when there is a real problem with gay characters in comedy elsewhere. The character of the mincing fag has returned to mainstream comedy for the first time since the 1970s, without Brüno's reflexivity. Horne and Corden have a gay war correspondent who spends his time shrieking about Dolce & Gabbana. Al Murray has a pink-clad gay Nazi who squeals: "I love to go undercover with the boys, Mein Führer!"

How are they different to Brüno? The judo throw of shifting the butt of the joke on to the homophobes never happens. They never make their gross caricatures interact with real people, where they can be exposed as absurd. They are presented – if you'll excuse the pun – straight. The joke really is, here, on the gay guy: look at his triviality! Look at his dirty lusts!

I am sure these comedians aren't consciously homophobic. Living in their liberal showbiz bubbles, they believe we're so beyond bigotry that we can safely caricature each other, the way we all tease our friends. As the writer Adam Sternbergh puts it: "It's a pose that says, 'We're so past things like racial and sexual epithets that we can use racial and sexual epithets at will'." It would be great if this was true: universal po-facedness isn't a victory for anyone. But we don't live in that world: gay kids are still six times more likely to commit suicide than their straight siblings.

This kind of stereotyping does real psychological harm – not just in encouraging bigots, but in shaping how gay people see themselves. I remember when I was a kid in the 1980s and slowly realising I was gay, seeing Mr Humphries or Larry Grayson or Frankie Howerd on TV – and no other gay people, ever – and becoming convinced this is what being gay meant. It's not just about fancying your own gender; it's about being effete and shallow. It was depressing, because I didn't want to be like that. I wanted to go to war zones, not catwalks; I wanted to talk foreign policy, not shoes.

The problem isn't camp itself. It's the implication that all gay people are camp, and that the two are inextricably entwined. Of course, some gay men are naturally effeminate – but so are some straight men. They should be free to express themselves without being jeered at or bullied; but they're not our only face. Now the closet is gone, gay people are increasingly like everyone else, and the outdated caricature can at last be given an honourable burial.

Brüno has started to lead the funeral cortège, by making the people who still believe in the stereotype look like fools – and getting tens of millions of people to laugh in their faces. Mince on, Brüno – you are mincing homophobia.

Shane Coleman is on leave