Claire is one of the few people that actually understand that Pintsize is not a rampaging a-hole. I mean she says as much. He's crude, he's rude, he enjoys shocking people... But he's also a companion AI. And really, he does help people. He does so while being crude, rude and nasty towards people. In a lot of ways he's like a old jester. He deliberately makes himself the butt of jokes to act as a goad and provide catharsis to those around him. He sets himself up to be a joke, even be abused... but he also amuses people and sometimes makes them think. He was there when Marten needed a friend. He's been there when Faye tried drinking herself to death. He set himself up the target for Bubbles' anger at the party, knowing full well it would go badly for him.. but it was something she needed before she was stressed to far and tried to disassemble someone else at the party. Someone's who's limbs aren't held together by magnets.
Sure, he enjoys shocking people. Collecting porn, grossing people out and engaging in minor acts of mayhem and teasing others are his hobbies. But he doesn't try to hurt people. He doesn't use his information against others in a mean or nasty way. In the end, he just wants to help.. in a round about way. Also, he's small and sneaky. Claire's around the apartment a lot. The chances are very high he already has figured out or knows that Claire is trans well before this.