Earlier quoted context omitted.
He forced his way into the conversation through terrorism. It seems reasonable enough to reject his ideas out of hand rather than give them respectful hearing.
With respect this is not correct. What you are describing is Ad Hominem driven by some kind of moralist knee-jerk reaction. The absurd extreme of this line of reasoning would be to refuse to acknowledge the existence of snow because Hitler mentioned in passing in a letter or a speech at some point.
Unlike Hitler's opinions on snow, Ted Kaczynski's murders are inextricably linked to his ideology.