Being well versed in the reciprocity rules of radio communication, I am puzzled by the differentiation being applied to transmitting and receiving here. Transmitter protection circuitry kicking in?
I offer that in military comm, the RX and Tx are often not in the same place. I wonder if the FAA might sometimes have similar non co-located facilities for their Rx, TX. That could explain the anomaly. Just a guess.
I did make an aircraft VHF transmitter half a century ago from 2n708 computer transistors and it sounded pretty good with even the proverbial coat hanger attached. Crummy VSWR alone should not effect audio quality other than lower the effective output. Normally one SHOULD expect a little more solid link TO the airplane because the ground station has an edge in power output.