I'm guessing the first thing teched after the race should be for a working and not disabled kill switch.
If you tend to it properly because it's an important thing on the engine you probably won't have a problem.
If you do anyway that's racing in the class you picked to race.
Disable or alter the switch and you should get DQ'ed.
Good thread and from now on if a racer i'm supporting gets beat and the other goes to tech, the first thing i'm going to expect to be checked is for a working kill switch. If it's not working then it should be taken apart to see if it's been altered.
Cheating is still cheating even if it's for reliability giving you an edge over your competition.