If he is in a public place, it isn't his space, now is it? Ask a lawyer if that would make any difference. Verbal assault, is still assault. The expletives and personal attacks, are not covered by free speech in the same manner as political opinions. Free speech does have limits, such as yelling fire in a theater. There are consequences for actions, and many of them such as "fighting words" and predictable trigger words such as " the N word" are not covered as free speech. (Talk with a lawyer or judge for any legal advice of course).
Screaming expletives in my wife's face, would be well over that line.
As soon as the big tough guy chest bumped the old guy he invaded the old guys space AND committed a physical assault! At that point the old man had the right to knock him on his ass and I wish he would have. I hate bullies and especially liberal bullies.
