What GSlob said...after all, he knows your thoughts and he's expecting you to compromise your position. Be polite, be kind, but be true to your principles. A pleasant response gives you creedence later on.
Well, rface's thoughts I do not know. More, he himself does not know them, for otherwise he would not be asking for the advice. So, I tried the logical approach: will he feel comfortable- if yes, then he should go and not ask. Will he feel uncomfortable? - he should not go then, and handle the thing nicely. Say, the jury duty, and regrettably just around the date. The only gray area is if his degree of discomfort is really minor. Under those conditions he can go, and no harm done.