I still have alot of gripes with the Lightbound and their portrayal. Because honestly, I think Grommash and the Mag’har orcs were most likely lying about the Lightbound suddenly out of nowhere becoming “evil” conquerors and the Mag’har totally did nothing wrong.
AU Grommash and a majority of the AU orcs and clans already proved that with minimial outside influence(and completely without any demonic corruption), they were some of the most barbaric and morally evil factions in Warcraft’s history, taking extreme levels of sadistic pleasure in humiliating and torturing, particularly civilians and innocents. They also almost immediately turned to necromancy, void magic and soul enslavement and defilement completely unprompted(Which was also Grommash’s idea).
TL:DR The Lightbound were and are most likely very much the good guys, and everything said in the Mag’har recruitment quest about them is a lie from already proven untrustworthy villains.