Unfortunately it is always a huge risk attending events just to see one person (even more so if you have no interest in the actual show that the event is based on), as guests can cancel at any time
Do you know any of the other guests? If you do then it may be worth attending. It's also possible that one (or more) of the other guests that ME are working on may interest you.
Never been to a covention I'm going to wait to see if the other guests are people I want to meet! Jason, Claudia, Joe or Michael would be great!