Sounds like if you just don't set gear down as a failsafe position for Spektrum systems, there will be no problem. Just have the gear in the up position when binding so the receiver recognizes gear up as the faildafe position. When the receiver is turned on without the transmitter being on it will go to the failsafe up position which in turn Tam's gear failsafe should override the signal. This would be the same as if you turned on your 72 MHZ transmitter with the gear switch in the wrong position hence the gear will stay down until the Spektrum transmitter makes the link. In that case it should also function like a 72Mhz system and not allow the gear to retract until the switch is cycled to the down position and back to retract.
You just don't have the availability to have the gear coming out as an indication of radio failsafe, but then you will have the audible shutdown of the turbine.
At least I think it should work this way.....
Have to go try it out in the garage.
BC