What I don't like is dumping full alternator charge current to ground while the engine is running . seems like the fusible link will end up doing its job a blow.
I don't think the alternator ever gets a chance to increase its power output.
Lets say the alternator output is 2.5 amps to the field and 3.5 amps to the ignition. Total of 6 amps out at 14.2 Volts.
Flip the Kill switch to off.
6 amps takes the short route to ground. Even if the voltage regulator sees a voltage drop in time to go full field, electricity isn't going to flow through the windings instead of the direct route through the kill switch. So the alternator never has a chance to go to maximum output.
I'm not saying grounding the alternator is without its faults, I just don't think the fusible link will be harmed during a test.