This is an older rig, a TS-700A, so I'm not too sure about it having any protection. The manual doesn't mention anything that I see.
I was hesitant to key the rig after I lost my load, I'll have to check the reading on the 700A meter VS on the SX-400. That would certainly explain everything as even the Calibration on the SX-400 depends on output from the xceiver.
I do have the parts I need to build a dummy load, but I did this first because I was eager
Maybe that was a mistake.