https://wow.gamepedia.com/A_Kingdom_...d_(WC3_Undead)
Sylvanas Windrunner: How could I not? For some reason I no longer hear the Lich King's voice in my head. My will is my own once again.
Sylvanas Windrunner: You dreadlords seem to know why.
Varimathras: We've discovered that the Lich King is losing his power! As it wanes, so too does his ability to command undead such as you.
And at that time Arthas was not the Lich King. Also the stuff happening in game does not always depict lore. For example I can't imagine a warrior getting rekt by a druid ingame the same way saurfang got rekt by malfurion (and before this derails into a malf vs. saurfang thread, I know he is an archdruid yadayada, but they way how weak they portraited saurfang against malfurion isn't the same how it would be ingame).
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I think everyone would be pissed/suspicious at someone fighting for their survival and getting left to fight alone against an enemy threating their existence.