Pretty foolish, getting mad over somebody for missing a raid, sad, sad people have their own lives they get in trouble outside of the game or banned from it, be mad at them all you want, I just think that is foolish. I doubt you guys are the world first crowd, so when you think about playing the game people like to enjoy video games, not find unpaid work and obligations in them.
If he is a liability kick him, if you need more people, find them, let the dude know as well he will have is spot lost or competed for a new person.