Thanks for the post, which is helpful. All three points are correct, although for #3, the gate agent is not violating any rule; he is following them.

Medallion members should be able to get a no-status companion -- if he or she has a Skymiles number (very important; must be at least Skymiles general member) -- on the gate upgrade list. Both of you will have to show up at the gate before the agent begins to process the list. Going to or from SFO, I think your companion's chances are slim. You should still try because the gate agent can move your friend to a better coach seat if there is no upgrade space. His or her priority will be after all of the elites.

I have been on some flights like OKC-ATL when all upgrade-eligible people were processed, and there was still empty first class seats remaining.