If you look at the events of Wotlk, she was asking the blood elves to help after they had their civil war. The leader refused and she basically told them that you either help the forsaken or you're the enemy of the forsaken... and no enemy of the forsaken is long for this world... or something to that effect.

Which is exactly why the Blood Elves shouldn't be goose-stepping behind Sylvanas while she raises their dead to be her thralls. The biggest reaction we've gotten from Lorthemar is him standing next to her like a good sidekick as they fly away in an airship, looking down at Lordaeron where just 10 minutes earlier she chemo-bombed a shit ton of Blood Elves just to raise as mass skeletons.