He has absolutely no concept of the startle response in PTSD sufferers and that's largely because he hasn't bothered to educate himself on the subject.
I don't think most women would be impressed by this even if they didn't have PTSD, and men know that without having to research it.
I've explained many times how my trauma manifests itself and that boundary pushing for sex is a huge trigger.
No woman should have to put up with this, trauma or no.
Minor but relevant detail here was that my rape also occurred on a sofa in not too dissimilar circumstances. Huge trigger.
Brrr, that's not minor. I'm so sorry OP

He doesn't care about your comfort, as you say, he's just obsessed with sex.
I said I know he doesn't care much for his boundaries (an example of this would be asking me to wake him up early by performing a sexual act) but reiterated that for me, it's imperative that I'm able to express my consent otherwise it's a huge breach of my boundaries.
I'm sure he does care about his boundaries, he just has different ones. Assuming his straight, how would he feel if a man shoved his genitals in his face to wake him up or something? Or whatever he isn't into (someone urethral sounding him without his consent or something.) I'm sure he'd have boundaries then!
He didn't apologise, he was probably embarrassed so he quickly changed the subject
He didn't even apologize.
The correct response to embarrassment at having done something wrong is 'oh, I'm really sorry' etc. So I don't think he was embarrassed at all, he just doesn't give much of a shit.
I don't think he has much of a normal emotional range/empathy, that's probably why he needs intense stuff to get off.