I'm going to agree with Mistress Kay here, I'm lost. I don't have pity sex with anyone. Regardless of their conditions. Could you feel sorry for some of Americas worst serial killers because of their childhood, and thus have sex with them out of pity?
Now, would I have sex with someone I fell in love with, even if they had a disability? Yes. That's different.
Pity sex is bad. As my mother said, the only person you should have pity sex with is yourself.