Probably semantics
In the setup for taking two unbalanced lines stereo and summing them to mono and then connecting them to an balanced input and not connecting the input to pin 1 at all but simply leaving the shield only connected at the mixer end, you have the situation where on the unbalanced stereo side you do have a "ground" which serves as ground reference for the signal and also for the shield and on the balanced side, you don't really have a ground, since the input circuit is expecting a balanced signal, with an independant shield. By using the shunt resistor, you are creating a floating ground for the Stereo unbalanced side of the circuit, but still allowing it to "float" on the input side of the balanced mixer input, and use the shield for the cable run.
Probably a poor use of terminology, personally I still like to simply use a transformer.
Sharyn
In the setup for taking two unbalanced lines stereo and summing them to mono and then connecting them to an balanced input and not connecting the input to pin 1 at all but simply leaving the shield only connected at the mixer end, you have the situation where on the unbalanced stereo side you do have a "ground" which serves as ground reference for the signal and also for the shield and on the balanced side, you don't really have a ground, since the input circuit is expecting a balanced signal, with an independant shield. By using the shunt resistor, you are creating a floating ground for the Stereo unbalanced side of the circuit, but still allowing it to "float" on the input side of the balanced mixer input, and use the shield for the cable run.
Probably a poor use of terminology, personally I still like to simply use a transformer.
Sharyn