One has to read between the lines here, but my take is this:
1. White was brought in to bolster DE depth. You have to run him the entire spring to see what you have. Between whatever portal conversations were had and navigating a new depth chart, I can see why you leave him there.
2. The move being made at this point (3 weeks prior to Nevada) tells me that White wasn't in the 3 deep at DE. At 275, the staff is guiding him towards DT. Based on his career at A&M, it might be for the best.
3. I don't think there are any expectations of him contributing at DT this year. I have to wonder if the "slide him back out to DE if we need a bigger End" is legit or lip service. We've seen it before (Townley, Vilbert) and in both cases it played out more like limbo than certainty.