While I agree that the Warriors did nothing wrong, I do think they got extremely lucky in that the salary cap swelled at the same time Durant became a free agent. That was just plain bad luck for everyone else—though I also agree that if Boston had done something similar, I'd be as happy as a pig in slop.
I see no good reason, though, to go out of one's way to congratulate the Warriors, especially on a Celtics board. Green's a jerk, and my impression of Curry and Durant is that they used to be nicer but have morphed into somewhat-jerky people.
And of course Durant said no—TWICE—to carving his own path: first, when he failed to lead his fellow Thunder to a series win against GS, and instead of coming back for a potential rematch he bolted to the enemy; and second, when he turned down the chance to be the man in Boston.
So, basically, he twice turned down the opportunity to really show his mettle and be the man, and instead latched onto Curry's coattails for a couple of easy rides to the title.