I doubt it. They both have a palpable hateboner for the horde and I could easily see them arguing that the horde should have done more to try and save Varian. Nothing short of sacrificing every horde soldier there would be good enough for Jaina.
I'll grant you those looking for slights would still find something, but at least it'd give
some sort of defense against it, surely you can see that, right? A token effort is better than doing
nothing and leaving the Alliance to their fate. All it does is reinforce the idea that the Horde is untrustworthy. Seriously, why should the Alliance trust the Horde after this? We players have the benefit of seeing both sides, but the characters ingame don't, so to the Alliance, its just the Horde failing them and saving their own hides over helping.
allies in that situation: 'cowardly sylvanas sacrificing peon with stick to cover her own retreat!', shrug.
besides, i think that if the demons have already killed the war chief and thrall is lying on the ground like a chump, then a peon with a stick isn't going to do very much.
You never know. One man could change everything. And like I said above, it'd at least help image-wise. But yeah, fine, Sylvanas did no wrong, rah rah Horde, lok'tar ogar (that means "screw you, I got mine!" right?)