ex claimed loud visitor, which is a role that can target someone at night and that person will receive a message saying they'd been visited. (an effectively useless role on its own, but can have implications when combined with other things)
if he uses his role successfully tonight, it will strongly indicate that he wasn't lying that he had it, but he could still be scum with that role, or the person he uses it on is also scum, and its also possible that even if he is town scum will just roleblock him.
I don't see the point in leaving him alive to possibly confirm an ability that isn't particularly AI to begin with.