The question is, what bid is United willing to take rather than process a GPU?
One might say, well, $100 cash is better than processing a GPU, but you start doing that nobody is going to pay your business fares....
It seems that given so much of the profitability of long haul flights is driven by business class revenue United can't risk undermining their own pricing too much.
Then again, if you take your paid loads from 80% to 100%, suppose you don't need the same revenue per seat....