I think there’s actually alot of interesting grey area in regards to that. Especially in a setting where some Dtuids can communicate in a very rudimentary way with just basic grass, much less something as inherently and intensely magical as a World Tree. It’s been a while since I read Stormrage, but I believe there was a part where Hamuul even heard Teldrassil whispering, and realized she had been corrupted.
Besides, in my eternal cataloguing of the Horde’s unforgivable sins, I’m content to add an extra degree of agony to the death they gave Teldrassil.