it is possible that a colgan flight is full with open seats, especially if there is cargo.

I have seen flights out of GRK go out 'full' with over 5 seats open due to being packed to the gills with cargo. So while it is possible it is technically showing a seat there, the flight could still be marked full. 9 seems a bit on the high side for amount of seats open yet still full, in my experience, but 5 or so, not.

BTW a small technicality, but Colgan would be a Connection not express. Many of them operate very differently than an express flight under at risk deals with colgan instead of a capacity purchase agreement, which means indeed Colgan wants every flight to be as full as possible so they make more money, flying empty for them means little to no return on the flight.