What you have is a customized neat wiring scheme where previous owner paired the magnetic sensor to the ground wire with a nice anti shafing fiberglass mesh.
Just remove magnetic sensor and you will have it back to original just as in the manual.
Because RevGlow applies current to the glow plug when it detects a signal below 25% throtle (or any channel it is plugged into)
By connecting to a Throtle Max, it automatically applies power when you are cranking the engine given ThrotleMax uses a sensor to detect engine RPM and sends signal to RevGlow to become enabled when RPM is low (such as crancking or throtle hold), thus avoiding eng shut down.
Without ThrotleMax you can plug into an usused channel and slave it to the throtle channel (mix) so that it mimics same curves and assigned to a switch. Since its switched, it will only turn on when mix switch is enabled. Depending on radio this switch can be your throtle hold, so when its engaged, so is the RevGlow.
~~Enjoying the hobby one flight at a time~~