Age is irrelevant in the law. "Come here and make me" implies violence. You don't have to think they can whup you for it to be assault. You must only have a reasonable belief that the person making the comment has intent to make offensive physical contact.
I think this guy (and my partisan butt keeps picturing Sen. Robert Byrd because I don't know what Rep. Stark looks like;)) crossed a line. I wouldn't have called the cops (Hastert was making fun a bit on MtP this morning), but I think all the elements of assault were present.
Of course, assault is a wussy crime in my view, but there it is... plus the guy was 72.
(A funny side effect of this would be the grey panthers opposing anyone who made fun of the fact that the GOP got upset over an "old" man.) :)