I wire all of the new builds to cut the fuel pump power. The modern car has so many relays, field wires, diodes, etc.
The only sure way to stop the fuel fire( and that is the reason for the power switch),is to drop the power to the fuel pump.
Remember Greg, AT idle the stop may be 2sec, at RPM the stop is right now.
Never had any issues at tech. Actually they like my cars, cuz they shut off.
MM
pS the VW does not need a field wire.. Most ,if not all, will self field @ about 3500rpm, engine speed.