United has nothing against props. In fact, they were willing to work with Colgan on the Q400 rates to keep them flying. The Q400 did around 10% of the express feed for United (not including CommutAir). It turned out in the end to be a cash problem for Pinnacle. No one seemed willing to lend Pinnacle the cash it needed to keep operating so it had to turn to Delta for Debtor in Possession financing. In order to receive the DIP financing, Delta set some pretty harsh restrictions for Pinnacle that included ending service with United.