"Throwing a pie is not in the same league as the kind of violence that is being talked about in the article. "

You are correct.  Throwing a pie is far worse.  It was REAL.  It actually happened.  The types of violence they're talking about in this article is imaginary.

"It's only a matter of time, it seems, until we are looking at the return of the violence against politicians that we saw in the 70s"

Says who?  You?  I can make stuff up too.