If you have an alternator up front, it will not kill the engine by the switch. The alternator will power the car with the switch flipped.
I may be misunderstanding you but every late model car with an alternator and an ECM is powered from the battery. The alternators only function is to keep the battery charged.
The drawing I posted works, is safe and has passed tech every time.
Passing a local track tech is one thing. My car can pass without any switch in circuit and no fuses. My buddy's car passed for years and the electrical was a death trap. I finally insisted he fix it.
If the alternator goes to the common point power feed for electrical up front, killing the battery will not stop the car. Things will run off the alternator without the battery in line. This is also terrible for electrical parts.
If the alternator output goes back to the battery, it is unsafe and not NHRA legal. It is unsafe and non-compliant because the heavy alternator wire will remain hot even with the switch off, and that is a fire hazard. Everything has to cut off according to rules.
The only way to kill an alternator car compliant with rules is to kill fuel, ignition, and/or alternator with one pole of a switch while the second pole kills the main heavy feed to front.
There is no other way to do it. It has to have a second pole.
I would never run a heavy alternator feed back to the battery in my car. I back feed the heavy main cable to the start relay/solenoid. I do the engine kill primarily by cutting fuel pump voltage, although I cut other things, and the large pole opens the heavy start cable that goes to the front common power point.