Most Mopar manual trans cars did NOT have one, including cars built before AND after the one in question. After wasting a thrust bearing in the 80s on a 273 I will NEVER start another manual trans car with clutch disengaged.
My personal opinion is that if you can't manage a manual trans without one you should be driving an automatic. I also don't know what the NHRA rulebook says about manual trans safety switches, but the few times that I've had a manual trans car at the track it was not asked about (but the last time was in 2002). I'd sure have an argument on a stock car without one.