some got quite a bit more Void pumped into them than others, but they still don’t like Void as a general rule since… you know, a Void Lord destroyed their home and left them force ghosts.
The only reason they would aid Xal’atath is if their Void infusion fully dominated their minds, same with Void Elves. Which, ironically enough, we have confirmation were what Nether Prince Dur’zaan was attempting to turn the Blood Elves into, more Void Ethereals. They just left more flesh than was hoped for.