I think that's a huge statement in regards to reality TV, because it can escapism to the extreme - living vicariously through others lives, as the attentive viewers of Truman's show so obviously do.
Think of Truman as a metaphor, an Everyman. The life he lives isn't his own. It's manipulated to fit a narrative - one driven by television (and by extension media as a whole). He's controlled, contained, kept complacent by the people behind the television show. They create fears in him, and then continuously reinforce them, in order to keep him complacent and afraid to break out of his comfortable world. And why do they do this? In order to sell products.
He's blissfully unaware of this for most of his life, and so he thinks he's happy - for the most part. But there's this little nagging memory of a moment when he stepped out of the world presented to him and experienced passion that truly came from within, rather than without. He lives with this for years, crushing it down, until one day he gets a glimpse of the constructed nature of the world around him. That glimpse is enough to get him looking closer, until soon he begins to see the signs everywhere and starts to wake up to the fact that he's been manipulated all along - and then begins to realize that he doesn't have to allow himself to be manipulated anymore. He chooses to follow his passion, to do what's important to him, rather than keep going on with the constructed world he's been presented with.
It's a satire of the american dream - the perfect community, the perfect house with a white picket fence, the perfect middle class job, the perfect wife, etc - as a construct of the media, foisted upon people as a means to sell products. It's a critique of television and advertising and the way it uses fear to manipulate people into buying the products it's selling.
The audience in the movie is just the expansion of this beyond Truman - they're invested in the story they're being sold and unaware that it's simply a means to manipulate them into buying the products being advertised, just as Truman is unaware of the story he's been sold and the way his life has been manipulated. His story is the idealized version of theirs, the one they aspire to, the one that seems like it might be a little closer if they maybe just bought the free range chicken he eats, or the beer he drinks, or the Chef's Pal 5-in-1 kitchen accessory. It's not escapism, it's aspiration.
Truman escapes the narrative he's been sold his whole life, and goes off into the uncertainty of pursing his own dreams, his own passions, his own direction in life. But what about the audience? They just change the channel, find another narrative to buy into, and continue be sold a bill of goods by the media who's only real concern is their ability to sell more products, and who will do whatever it takes to make that happen.
It's not about reality tv, except to the extent that it exists as a component of the larger world of television as a whole. There is no difference between reality tv and any other kind of tv, or any other form of advertising-driven media for that matter. They all use the same techniques - fear, idealized scenarios, etc - to manipulate the audience into believing that they want whatever it is the sponsors are selling. Truman is merely this manipulation made explicit; the audience is all of us, blissfully unaware of the way we're manipulated our entire lives by the people behind the media.