Because the mindset of town making an early vote isn’t “this person didn’t do awesome things with their early posts, so they must be a wolf.” It’s “this person did suspicious things early on, they must be a wolf.”
Jumping on a silly post that says something about scum being in the lowposters is a very low-level thought for a villager, and Flameo doesn’t come across as a very surface-level player.
I can’t believe I’m explaining this so elaborately.