Yes. But not if Mexico City ( i.e. central gov't) tells Minosa to get the opposion (PAN) on board. My guess that Nieto doesn't want any major hassle in his fragile majority. This is political not environmental. The ease thing for semarnat to do was just to reject this project, no? That was the path of least resistance.
If SEMARNAT wasn't satisfied with the "science" it would have been denied already. My feeling is that this is coming from the central government, i.e. Nieto (PRI) wants the newly elected (PAN) party in the region to be on board. This is why SEMARNAT did not ask for more information. Obviosuly not good in that there is still uncertainty, but the theme is different. This is now about jobs, royalties, etc IMO.