This is a hook-up that just had to happen. I mean, even disregarding the fact that they are two of the most talk about acts in recent times and, some might argue, two of the best in those very times...there's more to it than that.
Actually the true reason is largely historical. Salem and These New Puritans fit together quite well, what with all those Witch trials in the 17th century and the great Puritanical migration which occurred on the shores of colonial America. It's all linked! You see! Well, this connection made my day anyway!
Regardless, Salem have re-worked and rejigged the forthcoming TNPS single 'Hologram'. You may be aware that Heather Marlatt from Salem actually appeared on Hidden, you may not. But you are now. This is TNPNS repaying the favour. Or something like that.