This is a completely useless article, which creates more questions than it answers. Chiefly among them: why would a linguistic researcher believe that one shared property of Indo-European languages implies a universal grammar?
Of course just because language has deeper structures doesn't mean the structures are actually universal. I happen to like a lot of the syntactic mechanisms suggested by minimalists (the work on things like adjective order and clause relations is fascinating) but I don't necessarily believe it's compelling that any of it is an inherent feature in the brain...
EDIT: Here are some presentations by the authors, though I must admit I don't have the time to look though at the moment. http://www.hf.uio.no/ilos/english/research/projects/traces-o...