Well... my take is that you don't need a comeback. He DOES sound difficult. And a lot of us know from experience out here that other people are generally a lot less accepting of our kid's bad behavior than we are. In fact, I know our kid sort of trained us to put up with some of her bad behaviors for a while.
It is difficult to get him to adjust behavior in a group when you aren't there, but you absolutely determine how you as parents react when he has an emotional outburst or treats someone inappropriately. It seems like that is the first place for him to learn how to control his emotions -- then work with him to transfer those skills to other kids.
The Frodo Baggins story is just the sort of thing he will continue to encounter. When my D (now 17) was 7, she read the whole LOTR trilogy over a few month period. But I bet she did not have a single classmate who knew who Frodo was... his age mates are NOT going to understand him, likely for years to come. But I always figure as a parent, it is part of my job to teach her to be (if not gracious), at least reasonably appropriate and respectful with other people. And to seek an adult's help if the other kids are teasing/being unkind (don't just lash out).
