A couple of points — first, the tactics you describe were employed by Tea Party activists trying to shoot down the proposed ACA a few years ago. The Tea Party itself was created by the Koch brothers. This is where astroturfing began. And now the shoe is on the other foot. Don’t like the bed you’re now lying in? It was your side that made it.
Second, it’s true that Rohrabacher has easily won in this district in 2012, 2014, and 2016. However, in 2016, he got less than 60% of the vote in this “safe” Republican district (rare for him), and furthermore, this “safe” Republican district voted more for Clinton than for Trump in 2016. Rohrabacher might want to watch how closely he aligns himself with Trump, as that could be a deathtrap for him.
And third, by Rohrabacher refusing to hold a town meeting, he’s showing himself to be a gutless coward. Playing right into the hands of the protesters, who have successfully shown him for what he is.