Personally, I think the idea implied by the notion that the Blood Elves joined the Horde that much earlier in comparison to the Draenei, which also would require Alliance questing in Draenor to take place much later, a little ridiculous and likely evidence of an oversight in the book itself. This would not, however, be an appropriate response to Ariel’s claim because it would just be me asserting that something that very clearly is canon isn’t on the sole basis of “I think this is kind of ridiculous” - and Blizzard has never shied away from doing ridiculous things before.
At that point it occurred to me that the idea that the Night Elves were there in response to Kael’thas is itself committing an error that I very much like to call out in other situations:
More specifically - it would not make sense for Tyrande to greenlight a hostile spying force to land in Eversong because one fine Sunday she just decided to. Tyrande after all was cordial to Kael’thas and wished that his people would see their way to a brighter future. It doesn’t make sense that Tyrande would turn around and do this.
But it doesn’t matter whether it would make sense or not. Look to the authorial intent.
The authorial intent was to throw out some red meat to Blood Elf players, who nominally don’t like Night Elves. You’ve got the faction enemy right there - the situation paints you as justified, and this can be used as one of several reasons for why you support the Horde and not the Alliance. The humans were already covered, this pins down another large pillar in the Alliance. We’re good to go. So why are the Night Elves there? That’s a question that doesn’t really matter. They are there to be the bad guys to the Blood Elves’ good guys. Period.
So why am I back in this thread talking about this then? I think ultimately because this episode is part of a trend. Horde players like to complain that they are often hit with the role of the villain, aggressively asking Alliance players how they would like it, and hunting for any scrap of justification which leads them to do things like turning Taurajo into a meme. What I think gets missed in this conversation is that even if the hits don’t always land, the writers do intend to paint at least a certain part of the Alliance as the bad guys to the Horde’s good guys as justification for the Horde’s actions against them.
This is certainly not the only instance of that - and the trend might be something that I put into a different thread.