I used to go to a lot of horror conventions and my stutter was never really a problem. It certainly was never as much of an issue and I expected it to be. I have a lot of trouble saying my own first name and that is something that was asked every single time. Sometimes I stuttered a little and sometimes I stuttered a lot but there was never a single time that a celebrity was rude about it, if anything I think most of them went out of their way to make it easier on me. I feel like they meet so many people and a fair percentage of that number are pushy or unpleasant and they are just glad to meet anyone polite and respectful. They won't care about the stutter.