Well as it turns out, that tip from Jason about PPS was the key to the solution.
I ran CGPS and paid attention closely to what was being displayed at the bottom. CGPS was not working in spite of the presence of a GPS dongle. As it turns out, CGPS was attempting to use ttyUSB0 (the radio) as it's source of GPS info.
So I looked at /etc/default/gpsd and saw that ttyACM0 was correctly identified in that file however USBAUTO was set to "True". This meant that USB plug in devices other than ttyACM0 were allowed to be added to the GPS daemon. I flipped that flag to "false" rebooted and everything worked! So while I do not know why the radio was being detected as a GPS source, constraining the GPS daemon to only allow ttyACM0 is the solution in this case.
In the photos:
CGPS is functioning
NMEA is recognized as a system time source
FLRig is connected to the rig and happy