I don't like this quote. It is amusing but not very rational. It is not rational to ignore arguments because they were made by an awful person. It also isn't rational even if one thinks that an argument or set of ideas is not worth thinking about to actively refuse to discuss those ideas, even if one thinks that the ideas aren't worth considering. The first part of the quote is marginally defensible if Popper is very sure that Heidegger's ideas are a waste of time. The second part of the quote, about refusing to talk to people who defend Heidegger makes about as much sense as a religion telling its adherents not to listen to some specific critic.

(That said, while I'm by no means an expert on this matter, my general opinion is that Heidegger is a waste of time.)