ATC callsign does sound like "Tyler 91"
The E-6 cannot refuel others but it can be air refueled
There was no mention of refueling being done and no tankers were heard during that time. Trailing wire ops are done over the water and they were possibly doing that NW of San Francisco earlier in the flight. They may have held for 2 hours in the Denver area in order to remain in range of one of the radio sites they use for strategic communications.