Eh... I'm no expert, but I don't think that's how impotency works? It's not that you can't FEEL excited. It's that you won't get an erection when you do.
Also, sexual arousal aside, groping boobs feels awesome, so it's not like his personality would do a 180 like that...
I don't know, I somehow feel like this whole arc is...different. Has a different feel to it...