LogFAQs > #971605853

Kirby said because the back-up role specifically states they have powers waiting to be unlocked, they thought it was unlikely the Vanillas had "secret" unlocks that they weren't aware of.

I still think this doesn't exactly make sense. Because Kirby knowing their role unlocks on another player's death incentivizes them to stay quiet about it. The Vanillas knowing they might have powers if some secret condition is met would only incentivize every Star Vanilla to claim in hopes that they get to have more fun in the game. IMO that would be a very bad setup to have all your Vanilla outing themselves, so the idea of activatable powers being hidden from them was still a possibility.

Note that I don't think that means a Town Kirby with that role would come to the same conclusion as me, I just think it wouldn't hold up.