I'm a disturbed individual so I don't get offended by the stuff they post on 8chan, but I still think the decision to hold an AMA there was so dumb it's hard not to laugh at it. You really don't want to have an AMA in an environment that is as unpredictable as 8chan, where nothing is too offensive to share. I looked through some of the threads related to the THQ AMA and you have a whole lot of nazi-stuff, anti-semitism and racism, lewd pictures of very underage anime girls (yes they are cartoons, but still) and once in a while you stumble upon pictures of hanged blacks or jews. A lot of this is made as jokes, yes, but that is still not something you want associated with you. Most people know little to nothing about 8chan, it's a bit difficult to find for your casual internet user as it won't show up in a google search, but if they do go there and see what kind of content they have chances are the reaction will be somewhat negative. By that point it matters little if the people behind those posts are serious or not.
THQ Nordic fucked up, they fucked up hard; they fucked up in a sersiouly hilarious way but it is still a major fuck-up. Best for them to do now is probably to keep quiet and wait for everyone to forget that this ever happened.