I respect a coach who dares to call 'em like he sees 'em. I also think Stern handled it well by not fining him. It's refreshing to see him allow an obviously frustrated coach air out his concerns without reprimand.
Stern can fire him? I thought the Magic hired him? I guess I don't know how this works.
I'm not 100% sure on the details regarding what he can and cannot do. But basically, I believe he doesn't have the power to outright say "you're fire" but what he could do, is sanction and fine the team up the rear until they have no choice but to let him go.
Of course, that would be a risky gamble for him, as if he ever went that far in trying to wield his power over his owners, there may be some backlash.
But, like any good tyrant, he's doing it behind close doors and threatening them.