Why? UA is comping you entry. Buy a membership if you want more than UA is already comping. If all the GS at SFO were comped access at the SFO PL, it would be utter chaos. There are already complaints about wait times at the restaurant. Next would be, "I'm a GS flying to Medford, but I shouldn't have to wait for restaurant entry behind some no-status putz flying to Hong Kong on a full-fare ticket who doesn't want to eat UA airplane food!".

I would make an exception for GSs that actually pull money out of their own pockets for their travel, but no way to GS traveling on OPM. GS who travel on their own money probably have no problem coughing up for a membership, but would appreciate the gesture. The OPM travelers have little skin in the game and prefer to keep it that way. I don't think UA wants to get into those weeds, though.