I think history here has taught us that teams can and do lose players for various reasons. The occasional player for personal reasons. Some for lack of PT who want to transfer where they might get more PT elsewhere. Players get injured. You never know who and when, but injuries happen. It seems pretty smart to me that Kermit covers his bases regarding possible changes to the roster. For years now, his approach in this regard has worked out just fine as far as I can tell. The numbers all seem to work out in the wash.
While I do not recall any specific examples off the top of my head, I imagine coaches have to account for the fact that verbal commitments aren't binding. For the most part, I suspect it is as stated above with possible loss of someone for some unknown unforeseen reason.