Ok well let's use some logic here. If you get up off of the seat and the engine dies, that means the seat switch works as designed. I will never in my life understand why people are quick to call it "bad" when this happens....
The issue lies in any of the other switches, from the PTO switch to the neutral switch to the controller and/or wiring. The controller "thinks" that something is "on"-and then the seat switch is used; when you get off and the tractor "thinks" that something is "on"-it will shut the engine down as it is designed to do.
Reminds me of a customer years ago. They used the tractor to move trailers; and that's all it was ever used for. The #1 complaint from 'em was that the thing kept blowing a fuse and would just shut down during operation, seemed to happen about weekly. They'd bypassed the seat switch (which is a stupid thing to do) and left the wiring laying behind the seat. Also behind the seat was a couple of trailer hitches, one was a standard 2" receiver type and the other was a 5th wheel ball hitch-which weighed about 15 lbs. Well the whole problem all along was the 5th wheel ball-it was cutting into the wire causing a short circuit. But per usual, that surely can't be the problem, I'm wrong they're right. So be it, come get your stuff-which they did, and to this day they buy 20 fuses a week and just switch them out when one blows. Sometimes you can't fix stupid.