"that creates an apprehension in another of an imminent harmful or offensive contact." Whether the miscreants intended it or not isn't the deciding factor.
If these two idiots had approached their targets hollering actual threats
that would be different.
Merely hollering their father is wrecking or could wreck the country isn't the same thing. It's
rude,
it's likely unsettling or startling if it comes somewhat out of nowhere, and it's nothing else if not boorish
and immature . . . but it isn't even close to a signal of imminent harm or offensive contact.
Now, you don't
really want to argue that family members of an incoming president should be given
the same kind of protection all the little campus snowflakes demanding their politically correct safe spaces
get, do you? (Rest assured, Obama's kids and the kids of other office holders probably heard very similar
things from some people, and if so I'm pretty sure nobody thought anything other than those people were
exposing themselves as jerks but not exactly levying any kind of imminent harm or offensive contact against
them.)