The only reason why I'm cautiously not bummed with this move is that I assume Belichick is taking absolutely no **** from him, and is making that abundantly clear from the get-go. Because he's proven to be a give-an-inch-take-a-mile guy, so I really think the only way he's worth having around is if he knows he's on thin ice and actually cares (and I'm not totally convinced he does care).
As long as the Pats are ready to cut his ass the moment he steps one toe out of line, and there's no real significant investment impeding their ability to do that, the upside is enough to make me shrug and say "sure, it could work out enough to be worth the headache"