It seems that they have confirmed it to be available DRM-free.
From the Kickstater comments section.
We just updated our FAQ, there will be a DRM-free version. Since we cannot change a description of a reward, we will have to ask you at the end which version you prefer - DRM-free or some other like Steam for example.
and from the (now updated) FAQ
Will the game be DRM-free?
Yes, we will have DRM-free version! The rewards cannot be edited anymore but each backer will have a choice for either DRM-free or a digital downloadable copy.