There’s stupidity, there’s carelessness and there is ineptitude of such monumental proportions that is borders on genius. Now I would be the last person to assume someone who has to take a job dressing up as a Disney character was not very bright. The person could have a hundred very good reasons for accepting such employment.
On the other hand, the kind of person who signs up for the job and then fails spectacularly to live up to the job description probably deserves no sympathy. Even so we have to feel a little compassion for this dork.
It wouldn’t be inappropriate to ask “What was he thinking because he obviously wasn’t.