Well at least the small aircraft was cleared to enter the runway
Again, no it wasn't.
Denver Center provided an IFR release to the aircraft. It did not clear it for takeoff or "to enter the runway." It can't, it wouldn't, it didn't. It is an uncontrolled airport, and having gotten an IFR release, the pilot would be expected to tune back to the airport advisory frequency and talk to local traffic before taking the runway.
I'd expect to hear the Denver ARTCC tapes this week...
Dave