My first thought was he had done something bad when he was already on double-secret probation and was told to go (a la Coe & Irving). But based on Rhoads' statement and him staying in classes, it does seem to be just a playing time kind of thing.
But if it's playing time, why wait clear the hell until now on the cusp of the season? Why go all the way thru summer and then fall camp? Is it just to preserve a year of eligibility at the next school? I guess that would make some sense. But as others have noted, the DL is definitely a rotational thing - he would have got a lot of snaps, starter or no. Or maybe not, IDK.
And it does remind me of Gannon from last year, in the timing and bewilderment aspect.