I often see posters about the forum lamenting that Stormheim wasn’t the reason for the war starting as opposed to Sylvanas being herself. I myself find this to be a very flawed argument that requires copious amounts of plot induced stupidity to be hefted upon Anduin, Genn, and the horde as a whole (some of which we actually see when Saurfang uses it as justification but that’ll be for later).
If Stormheim had been in some way used as a rallying cry for the horde to take up arms against the alliance this would likely lead to Anduin reprimanding Genn at some point for it, or at the very least inquiring about it. The problem here? Genn’s alibi is ROCK solid. All he has to do is say that he intervened because he recieved a letter from the alliance champion in Azsuna claiming that Sylvanas was sabotaging their relationship with Odyn and thus endangering the world by putting the Aegis of aggramar at further risk. Then as proof he’ll cite that she really was trying to enslave one of Odyn’s val’kyr and whether Odyn cares about them or not, isn’t much of a concern at this point as the horde and alliance should be tip-toeing around any faction that has one of these artifacts they need to open the tomb while they court them to gain access to it.
Then Anduin and/or Genn can send a letter to various horde leaders about Sylvanas’ actions in Stormheim and at best she’ll lose some support. At worst they might rebel against her for putting them all in danger. The only piece of genn’s alibi here that might be weak is that he didn’t necessarily read the letter but he could easily claimed it was lost when the skyfire crashed. And even if it does happen to be found it would only further vindicate him. It’d require copious amounts of plot induced stupidy for Genn to somehow not be able to justify his actions while Sylvanas could justify hers. If anything Genn would come out looking like a hero while Sylvanas more of a villain.
Speaking of, this would also make the entirety of the horde look like idiots too as it’d require them to either be totally fine with her enslaving one race/person for the sake of gaining immortality (everyone dies, just because the forsaken go mindless first isn’t an excuse), or kept in the dark about the whole affair which is why it makes Saurfang look bad. Yeah, they tried to kill your warchief… because she was up to no good ya dingus. At least in our current scenario we can say Saurfang not knowing about her activities is somewhat reasonable as the alliance at the time had little reason to inform the horde as a whole of her actions there (any moves made in this regard could have been more easily seen as propaganda and pushed them closer to war).
Lastly, Sylvanas burning Teldrassil not only wasn’t Plot induced stupidity as its something totally in line with her character as she was totally fine with blighting the whole of gilneas (of whom its citizens only escaped due to a secret passage), Southshore, and has been entirely fine with the torture and killing of peoples since vanilla. But it also wasn’t plot induced stupidity as it wasn’t a move that would cause the horde to turn against her; as in this very patch Lor’themar notes that Sylvanas has the hearts of the people of the horde. Meanwhile the schism he mentioned half a patch ago was apparently only in reference to a couple racial leaders and moreover said schism only got worse because she imprisoned Baine had that not occurred she’d have been one of their more beloved warchiefs apparently. That is to say, in terms of earning the horde’s loyalty Teldrassil was a brilliant move, because as it turns out they like that sort of thing.
EDIT made on 7/26 : Seems like this post didn’t really get across the point I was trying to get across. So here’s a TL;DR : If Sylvanas told the horde they’d be declaring war against the alliance because of Stormheim and this reached the alliance be it before or after Teldrassil. The alliance and Genn could easily justify his actions thanks to the end result and the ambiguity regarding the information the alliance would have had at the start of this campaign.
That is to say, the alliance could easily lie and say Genn knew about the Helya deal from the start and Sylvanas would have no way to refute this. Moreover, the alliance could easily bring out Eyir to speak on their behalf.
What i’m trying to say is, the only way Stormheim works as a reason for the start of the war: Is if the Horde is not given the full story and if the alliance doesn’t really respond to Sylvanas reason to declaring war.