If you look you can see the shirt in the trash can with blood on it, though he probably did want a moment to himself. Seems to me he's becoming conflicted with his feelings
I think that Yashiro was turned on when Doumeki started to wipe him down that's why he went into a fetile position so that Doumeki wouldn't see him. Yashiro made an excuse to make him step out so he could finish in private.
Yes! That's exactly what I wrote in my comment above. (sorry for not noticing your comment first! :(
After reading all this, I'm starting to wonder if Yashiro's shirt really was covered with blood or he just wanted to get rid of Doumeki...?