Why is Jason fake? Because Charlie said so?
Is there a reason why we're trusting the word of a jilted woman with an agenda prone to delusion over our own eyes? A woman who has been caught lying about Jason before? (She calls Jason a gameplayer but then tells Andy that she didn't use that word, just said he's acting different.)
Big Brother is meant to exist in a vacuum. Why should it matter if Jason is a different person outside of the house? It's a show. We refer to the housemates as "characters". How the hms conduct themselves outside of the confines of BB (aside from extenuating circumstances of disturbing acts warranting ejection) bear no relevance on BB. That's why image rehabilitation is a leading motivation for CBB contestants. Shit. That's why Jim Davidson won his series. He was able (for the most part, not entirely) to temper his inner misogynistic asshole.
If Jason isn't truly a nice guy, and has adopted that persona for the purpose of Big Brother, more power to him for keeping it up. Nearly a month in, there would be some real, firsthand evidence of his mask slipping (see early favorite and shrieky, manufactured romancer Jackson). If Jason was the chosen one and just received a generous edit, we would hear something in housemate chatter of Jason behaving differently than he is being portrayed. But as of now, how Jason has conducted himself in the house and how he is being edited via producers is basically on par - the tin reads the same. Even Charlie - in all her bitter, well-timed (after being turned down in the NICEST WAY POSSIBLE) assertions that Jason is different and not as he seems - qualifies her claims as outside the house meaning the Jason that we are seeing as viewers and the Jason that the housemates are living with 24/7 are the same. It's really just unfounded nonsense meant to sully house and viewer opinion on him thereby allowing her to gain more sympathy. It's a tactic plain and simple. And if you mind her pattern, she'll actually retract anything negative she says about him in a whisper.
Ultimately, I don't care if Jason is fake because I won't be following him outside of this show. Right now, what matters to me is that he seems a nice bloke, level-headed and caring. And if this is Jason playing a game, well isn't this the most innocuous strategy one can employ? Step 1. Don't make an ass of myself on telly. Step 2. Look after people. Step 3. Hope to win votes. I really can't fault that logic.