Many people don't see 4chan as much of a threat anymore, due to the way that net literacy has settled like a piss soaked blanket onto a majority of the populace. But what these people fail to realize is that 4chan has not grown softer, the rest of the world has grown harsher.
People used to go on 4chan as a break from having to keep their identity up all the time on other sites where your name, address, and sometimes phone number is attached to everything you say, but somewhere along the way, either with Project Chanology or the Occupy Wallstreet movement, people brought their shitposting, ironic or not, back across that proverbial border between the sites. Facebook used to be people playing flash games and keeping in touch with others, Tumblr used to be an art platform for people who didn't like deviantart, and Twitter used to be for people to post whatever random thing was on their mind. Now all these sites have become proxy warzones for those who are either for or against 4chan and what it stands for. And even within these two sides are warring sects, such as those who are against /pol/, the Politics board, and not the rest of the site, or those who hate the idea of it all together.
Dethklok's presence on the platform will give the people a direct link to them, primarily to Mr. Murderface who has elected to become a "tripfag" and attach his identity to all his posts. This will only lead to further turmoil amongst the fans as they may realize the sides they have to take, especially those who are regulars on 4chan with no interest in the band, as few as they are. We could be looking at a public demonstration that rivals the wet nightmares of all the people at Fox News.