I Only know of 4chan, but even than I know if it begins with a number and ends in chan it's highly suspect. And the guy didn't look through that site to see if anything was amiss prior to this? So many questions.
8chan is much worse than 4chan. It split off a long time ago and has a somewhat different format where people can make their own boards to discuss anything. It shouldn't be much worse in theory but the lack of moderation meant really bad stuff could find a home there from time to time, though I think 7chan was overall worse in that regard. The other big strike is when GamerGate blew up, got all the shitheads harassing people, and was subsequently booted from 4chan they moved to 8chan where they've lived ever since.
I used to browse 4chan's video game board /v/ a lot more, once the politics /pol/ board came into existence it slowly poisoned much of the site. At this point only smaller boards like /toy/ and retro games focused /vr/ are really worth checking out. It was bad in the past and you had to tune out the offensive shit the edgelords would say, but I still think there is some merit to being able to discuss topic anonymously. It prevents the circlejerk that Reddit tends to promote with it's upvote system, or the cliques you see form in forums like ResetEra or even here on CAG.
That said, hosting an official AMA on one of these sites is the stupidest things I've ever seen a PR person do. I imagine the guy probably just wasn't familiar with 4chan since THQ Nordic is based in Europe, but even two minutes of looking at any board should have been enough of a red flag to not do it. Especially once it started and he was getting slurs and hentai questions within the first few posts.