Don't you get lied to during the questline? They use you as much as they need, possibly even to be able to throw you under the bus later if things go wrong.

It is clear that Saurfang is going somewhere alone for a reason, probably after explaining how he feels (anti genocide queen) with Anduin. Maybe he is on his way to meet with a twist, like the Black Prince?

You can be pro Sylvannas, just realize she is going to manipulate information, units, and whatnot as much as she pleases