I haven’t seen a single Horde player excuse it. Not a single person arguing with your single-minded viewpoint has acted as if Teldrassil was anything other than the atrocity that it is. At most, I’ve seen why some have commented why the Horde leadership did not move against her; that’s it.
The Horde is in the belief that the Alliance is in every bit as invested in a War of Annihilation against them, as they are currently against the Alliance. There is a tangible fear that turning on each-other when there is a World War would only lead to them getting destroyed by the Alliance; even if they managed to succeed in toppling the Sylvanas regime. Thus, no matter their feelings on Teldrassil (and as far as I can tell NONE of them approve of it outside of Sylvanas loyalists) they feel cornered.
Long story short, they’re trapped. Teldrassil served remarkably in not only investing both factions into this war; but also silencing dissent within the Horde itself, ensuring Sylvanas maintains control. The other races of the Horde aren’t about to betray Sylvanas if all that means is getting destroyed by the Alliance. So, if the Alliance really wanted to give them the freedom to turn on her, they’d back off and reinforce their positions after Dazal’alor (giving any rebellion stewing breathing room to grow).