I agree that editing other people's comments isn't the best thing to do, but the README clearly states that those types of comments weren't welcome.

In addition, serious opinions like issue #60 weren't edited, only issues like #77, which literally said:

"Dear Beef, Beef. Thanks, Beef" -- https://github.com/upend/IF_MS_BUYS_GITHUB_IMMA_OUT/issues/7...

EDIT: ... and IMO calling an obvious troll a "troll" isn't defamatory. What GitHub is doing is clearly censorship, nothing short of it.