If that grey shirt offer was serious, if they think he is that good, then he should be good enough to get a scholarship this year, especially since there is now some room in the class.
If they decide not to make it a 2015 scholarship, I guess they don't think he is that good. Either that or they did something stupid like promising Lockley he would be the only signee for 2015.
The gray-shirt discussion predated Locksley's decision by a good bit, and also happened while Gentry was already recruited and committed. It would be a stretch to say that the two were related.
If you want to win championships, this is a key position. We have been lacking at quarterback for some years now and need to exhaust all possibilities for our starter. Charlie should get Merrick in the mix and let's see what happens.
Other issues could be relevant. Merrick has only recently begun devoting himself to football. Maybe he WANTS another year before his eligibility clock starts ticking -- more time on the weights and working with Kevin Murray. Another issue would be practice snaps and coaching time and how to divide it up among a quarterbacking crew that needs lots of coaching and practice reps.