Earlier quoted context omitted.
It's completely untrue that "no one who has the ability to not be autistic, would choose to be"; plenty of autistic people are happy to be the way they are and would not want to change. (Pedantic note 1: If you're super-duper-literal about what you said, and take it to refer only to people who actually have the ability not to autistic, rather than speculating on what would happen if autistic people had the ability no…
> plenty of autistic people are happy to be the way they are and would not want to change. How can you objectively claim to prefer autism over non-autism if you've never experienced the latter? It's like me being completely content with my mechanical Ford Mustang and refusing to switch to a computerized car on the grounds that I'm happy with my Mustang and it's impossible for me to imagine what driving a computerized…
I could be wrong -- it might be that hairdressing would suit me much better than I think, or that having the extra money would lead me to make decisions (earlier retirement? moving to a larger house? a generally spendier lifestyle?) that would be bad for me. But I have, or think I have, a pretty decent idea of how my life would be different if I were a hairdresser or $1M richer, and I can compare that against how things are now and make a reasonable guess at whether the change would be an improvement.
It doesn't need to be a matter of X being objectively better than Y. Would I like to be obsessively interested in fashion, celebrity gossip, and sport? Nope, I'm happy being a geeky intellectual type. It's entirely possible that those other folks are happier than I am (for the avoidance of doubt, I genuinely mean that and can think of some fairly plausible mechanisms that might make it so); but I'm used to being the way I am and have no wish to change in that way, and it would be a big upheaval in my life if I did.
Would I prefer to be autistic? Nope, I think it would be a nuisance and in any case I've grown used to being how I am. But I can (or at least I think I can) imagine being autistic and feeling much the same way about becoming not-autistic as I now feel about becoming autistic.
Severe autism is a big disadvantage in life and I think it's defensible to say that even if some severely autistic people wouldn't want to change that's a mistake on their part. But there's a whole spectrum, and over at the not-so-severe end any shift has both advantages and disadvantages, and I think it's very reasonable for someone to say that they wouldn't want to give up the advantages to get rid of the disadvantages, and that in any case autism is part of who and what they are and taking it away would mean taking them away and replacing them with someone else.
Incidentally, I think it's also perfectly reasonable to say "I like the car I'm driving now; I've had it for years and grown accustomed to its foibles; it's nice of you to offer me that extremely different car with a bunch of features this one doesn't have, but they don't sound very useful to me. I'll stick with the one I know I like, thanks." Someone who says that might turn out to be "wrong" in the sense that if you gave them the new car they'd eventually be glad you did, but so what?