Random thought that’s not so random anymore:

What if the Exarch Hellscream in the Tyranny of the Light scenario isn’t actually AU!Grom’s son but MU!Garrosh brought back to life and lightforged by the naaru as an example to set for the Mag’har that don’t fall in line with Yrel and the Lightbound, hence why he’s considered a “traitor”.

On the other hand, thirty years have passed between WoD and BfA, so the most likely outcome is during that time AU!Grom made his penance during the Iron Horde days, made peace with the draenei, and married another woman who birthed Exarch Hellscream (who I won’t call AU!Garrosh, because AU!Golka - his mother - died in pre-WoD, and for all intents and purposes the Exarch may not even have been given the name Garrosh by AU!Grom).

Although if Calia being lightforged undead is enough to bring on the salt, I’d be sadistically curious to see how volatile the reaction of an orc - the Garrosh Hellscream - getting brought back in the same manner would be.