Side note, he was an extremely talented math nerd and his manifesto did raise some interesting questions about technology and society.
I wouldn't exactly call him a "mass murderer", he only actually killed 3 people over a 17 year time span. IMO a "mass murderer" kills a lot of people all at once in a single location, for example, like McVeigh.
He only successfully killed 3 people - he definitely tried to kill more. That has to enter into the calculus. Not only that, by sending his packages through the mail he endangered many many more people in the process.
Relatedly: What's the threshold for you for body count before someone loses credibility? 5? 10? 100? 1000?
When someone goes unhinged and starts a mail bombing campaign and then threatens to kill more people if newspapers don't print his unhinged rambling manifesto then yes I think it's very important that every mention of him be paired with understanding of the lives he ended. Fuck him. I'm glad he's dead, and I'm glad he rotted in Supermax first.