Hi dinows,
Older mowers like your previous simple design Murray had practically no safety switches. I think people had more sense to understand a machine back in those days. Now everyone (machine owners) is looking to cash in by filing lawsuits to hide the fact that they were a true idiot.
Reverse PTO (RIO) shut off switches were mandated some years back after people were recklessly backing over kids, pets and bystanders. I've even heard them called "Lawyer Switches" a couple of times.
I cannot advise bypassing any safety switches.
I'm skeptical about even letting some young adults on any kind of rider or zero turn mower these days, the common sense is just not there anymore.... Having no sense of responsibility is dangerous to anyone around them.