Come on, this isn't a CYA paper. It's a genuinely interesting subject. which wouldn't have garnered nearly as much as attention, if it hadn't been spun and, like Archimid says, most so by that Nature article preview.
The fact is that this just isn't all that exciting. First of all, no one has ever said that all of recent Arctic sea ice loss is caused by AGW. Not because it isn't, but because we can't know for sure (although the downward trend definitely wouldn't be so steep if it wasn't for AGW). Secondly, there have been many more papers trying to pin down the amount of human attribution as compared to the AMO, the PDO, etc.
Climate risk deniers are dumb to spin this, because it automatically means they acknowledge the climate is changing. And Arctic sea ice loss is most probably just going to continue, especially if that 60% figure is wrong (which it might very well be), and so the consequences of this loss will become ever clearer.
Climate risk deniers are sad, old, selfish, white men with an authoritarian streak. It's best to ignore them, and not get worked up too much.