Remember something else that bugged me. That bit in the Engine Room about people not being able to touch each other or time.. reasserts itself? And they fast forward to zombie status?
I just figured out this whole "no touching" rule now. The Doctor wasn't saying that people shouldn't touch each other in general. Rather, he was specifically addressing the two Van Baalen brothers (Gregor and Tricky the "android"), telling them that they shouldn't touch each other. Here's why:
There were three zombie creatures...a standalone zombie creature, and two zombie creatures that were always connected together (like they were conjoined twins). The Doctor refers to the standalone creature as "she", which I figure means he has a pretty good idea it is future Clara. Therefore the twin creatures must be Gregor and Tricky. In order for the twin creature to form, Gregor and Tricky had to be holding onto each other to be fused together like that. The Doctor figures that if the two brothers don't touch each other, there is no way the twin creature could be formed at the moment (since it must be formed at some future time when they are
touching), and hence it would delay the formation of the twin creature (preventing the already-occurred timeline from occurring). Notice that once Gregor and Tricky do touch each other (when Gregor grabs Tricky by the arm) they burn and fuse together to form the very twin creature. (this is Time re-asserting itself)
I agree, it's not the greatest reasoning, but I think that was what the writer had in mind when he wrote the scene.