I see others have mentioned it but if you're at the cross roads of investigating asd and odd, I would also look at pda which might be a better fit than the asd/odd combo
My advice from our lived experience would be to not react hugely to this - which I know goes against how you feel but hear me out. Slightly bored and irritated, dismissive - "until you stop swearing, I can't help you" rather than a huge reaction can be more effective. "I don't talk to you like that and I don't expect you to talk to me like that, now go away.". In our family, we did very little punishment because it didn't work (as you say, you run out of things to take away, it increases anger in the house in general and it dust work). It actually became a model for dc and they copied imposing punishments when they were displeased.
i would also be very very straightforward on what words they cannot use. It takes the power out of them. A list of them all up in the wall. Define each one with them when they use it. When Dc was saying fuck, I asked why they was bringing sex in to our conversation. Did they want to know anything about sex? Bitch - how am I a female dog, what kind of dog am I, how silly, does that mean you're a puppy?
By changing my reaction and sounding slightly bored and irritated, rather than a huge emotional response and by keeping a steady message - "I don't talk to you like that, dad and I don't talk to each other like that, and I don't expect you to talk to me like that. We don't use fuck / bitch / cunt in this house.' - we stopped this phase.
At 15, dc (with pda, asd, adhd) doesn't swear at all. Its not as satisfying as shouting and punishing, but in our experience, it did work. And you said that you thought the diagnosis which you're pursuing wasn't relevant. It's entirely relevant. It couldn't be more relevant.