Look even if you are to get me to agree that Sylvanas is evil, sure It’s true that the road to hell is paved with good intentions, but there is nothing more important than the freedom of the individual and anyone that stands in the way of that, needs to be wiped out, as there’s no room no matter how infinite this universe for those who want to take your freedom away. That’s pretty black and white to me.
What you have to think about also is that the Horde actually needed Syvlanas during the time she was Warchief. Even if its true that Sylvanas has moved beyond mortal concerns, the honest facts were that after the war with the Legion, Sylvanas asked Saurfang a very important question. Could the Horde conquer Stormwind? The answer was no…in contrast, Orgrimmar was in fact much more vulnerable to an attack from the Alliance at that point in time.
So when Saurfang was there with an army of traitors and whatnot, if a siege had happened, Orgrimmar might have been able to hold the line, though just barely. Before Teldrassil happened, the situation was that Stormwind could defend an attack, but Orgrimmar could not. Sylvanas was absolutely correct at the time that after the war with a Legion, that the threat of ‘mutual destruction’ was no longer feasible. If you think about it, if the Horde had all of Kalimdoor to itself, the Horde would have been in a strong military position. The Alliance was therefore meant to be divided militarily against a unified Horde, and to a large degree that’s exactly what has happened, as Tyrande has gone off doing her own thing you see, leaving the Alliance forces divided.
Oh and by the way, Teldrassil was in fact a legitimate military target; you see, the Alliance could have used Teldrassil to transport azerite between Kalimdoor and the Eastern Kingdoms, which would have made the Horde incredibly vulnerable. There’s also the fact that all Sylvanas wanted was to demoralize the Alliance, and if Saurfang had killed Malfurion Stormrage, then the rest of those ‘innocents’ would have been spared, the whole point was to split the Alliance apart, killing Malfurion would have achieved that, but due to Saurfang’s blunder, more extreme actions were necessary. So you see in reality, the blood of the innocents of Teldrassil was on Saurfang’s hands. And while the Horde has been set back a little bit, Orgrimmar is strong and able to defend itself from an Alliance attack.