It's been previously established that Taishan is confused by the concept of relationships in general. I could rp this as being so busy he never had time to work on his own feelings, though. This would fit with how I've rped his various traumas.

Another option is to take inspiration from one of the other players at the table, since theres some implied S.A. in Taishan's edgy as hell backstory. It is possible that he's confused sex trauma with actual asexuality. Even though this is the more logical route to take, I don't want to potentially trigger the other player since they are currently getting therapy for exactly that trauma.