Because we should use our cop to copscan people?
Scanning Ezio means either:
You gain info we already got.
You learn Ezio is town when celaph says he's scum, and either claim to trade your life to daykill already caught scum, or you stay silent and let Ezio die, meaning celaph dies the next day.
You learn Ezio is scum when celaph says he's town, which is the only case in which there's any benefit at all, but you could just as easily scan someone not in question for the same benefit if they're scum and a greater benefit if they're town.