These exceptions were intended to be exceptions, not the rule. Obviously United is "cracking down" not because they despise GS members, but because the informal blogosphere publication of "rules" surrounding these exceptions (such J>2) is creating expectations, and ultimately displacing revenue. .....
Only UA has the data but if companions were becoming a significant portion of GS upgrades or some companions was getting a significant number of upgrades due to these exceptions, this may have caused other GSs to miss-out on upgrades or as you mention decrease the revenue sales opportunities. So this may come down to making one GS happy made another GS unhappy -- a dilemma for UA. The excess of PlusPoints in the eco-system has not helped.
Perhaps a more manageable situation would be to cap the number of companion upgrades for a given GS, X wildcards. Perhaps have tiers levels.