That senpai certainly awakened to something - I wonder was that enough to be considered " doing something lewd at school" because if so that is one hell of a way to sabotage the enemy
I do think he takes his curse removing job a bit TOO seriously, he didn't need to remove Kotobuki's bra at that point, he could have waited until later and then the bra wouldn't have gotten stolen leading to Tsubasa being cursed now. I may be wrong but it seemed like that's the flow of what happened.