I mean, there comes a point at which players sort of "earn" the right to respectfully retire as a "one team player" if they wish to.
And in the case of Ovechkin, at this point...the Caps are really only going as far as he can take them. Which probably isn't very far these days. But i don't see why he'd have any obligation to waive his trade protection just to "help out the franchise".
Those sort of "full rebuild" situations tend to just happen more organically than that anyway. As guys like Ovechkin, Yoshie, Carlsson age out...they'll get there in the next few years regardless. Unless they make some absolutely stellar "retooling" moves in the meantime, and enormous gambles like PLD pay off somehow.