And to take it one step further, I'm not even 100% sure that he came right out and actually said this at the beginning of TC.
I think it was implied and assumed by some of the sportswriters and forum posters, who likely thought it was the same situation as OTAs.
For all we know, Belichick may have expected Waters there a long time ago, and may have only had a deal in place to miss a small portion of TC in the beginning.
I certainly doubt that Waters had the green light as so many have said, to sit home throughout the entire camp. I could see a portion in the beginning, but not more than 1/2 way through camp, that never made much sense to me, but so many assured everyone that it was okay it was hard to feel negative about it.