Oh, I've giggled at my reaction to this thread.
I read it the OP and thought, 'Shit no OP, run for the hills. That's far too much for you deal with'.
Then I carried on reading a bit. Then I thought a bit. Then I realised that it all sounded familiar.
I have mental health issues (medicated, relatively controlled, but pretty serious), I am bisexual, I have had offending behaviour in my youth (linked to childhood trauma), I have 'serious' sexual fetishes (some related to pain).
So my advice appears to be not to ever date me. Sorry chicken.
Seriously though, I get it. It's a lot of stuff, and you clearly aren't comfortable with it, for whatever reason (though please could the whole 'more likely to cheat if you're bi' myth die a fucking death ASAP), so you are entirely within your rights to not date him. Like I'm entirely within my rights to not want to date someone who wouldn't get my regular sci-fi film references, or can't take the joy out of simple things in life.
I'm not to everyone's taste, clearly, no one is, and the trick of relationships is compatibility. Not one person twisting and turning themselves into something else to fit the form the other person needs. That's not sustainable. You're not compatible with him OP, that's not on him, or on you, so you should just walk away.
I do think your 'red flag' terminology was unfortunate, though I get you were using it loosely. I suppose the youthful offending could be worrying, but there's plenty of people out there who were dicks as teenagers and sorted their shit out. 'Red flags' to me are more related to potential indicators of DV or general arseholeness.