I'm wondering if none of the people who are saying "But it said Charles Xavier/Einstein/Cleopatra so everyone knew it was fake!" have ever heard of balloon debates.

In a balloon debate, a bunch of people are assigned characters - may be fictional, may be historical - and have to argue for an audience why they shouldn't be thrown out of a hypothetical sinking balloon. And people get really into it - for example a Harry Potter one where people dressed as their characters. I once chaired dressed as Death, and someone else chaired several times as Anne Robinson.

So especially at a con, with the amount of cosplay, I'd just assume they'd got someone who could do a decent costume and would be appearing in-character rather than as themselves.