Sorry, it isn’t.
He didn’t ACT on it though. You might find that I did not condemn Saurfang for speaking out against what Sylvanas did. It only became a problem when he literally betrayed her. Yeah, Vol’jin did screw up with Garrosh, talking all manner of trash to the Warchief, and probably instilling his hate in trolls at that moment. So Garrosh was justified in booting Vol’jin, but at that moment, Vol’jin is no longer a traitor, he was not part of Garrosh’s Horde (as Garrosh himself said.) Thusly Garrosh had broken away from the original Horde and made his own, Vol’jin and all the members of the new Horde, decided to ally themselves who also saw Garrosh’s new Horde as a threat and beat them.
They already have been excused, you saying so does not make it so, sorry buddy.
YOUR identity of the Horde, She isn’t thrall, she isn’t a Orc, she isn’t a troll or Tauren, she is undead and is leader of the Horde, she has done nothing to purposefully and with malicious intent harm the members of the Horde. Did a few soldiers die as collateral so that the majority would not be slaughtered? Yes, she did. Which is justified.
Raising mindless undead? I point to you back to the Val’kyr who states that only the willing can be raised.
Derek is the only point you have, and one can make the argument that Derek was never meant to be a Forsaken, he was meant to be a tool, nothing more.