Say I’ve been flying my plane, I land it, pick it up then without thinking turn my radio off. Will the plane enter rtl in my hand? Are there any options I can check to prevent the motor firing up accidentally?
There is some code to try and reduce the risk of this happening, but you should not rely on it. The code tries to detect if you are flying before it allows the throttle to engage when in an auto-throttle mode like RTL. It is however a surprisingly difficult thing to reliably tell if a plane is flying or not. The heuristics used involve ground speed, air speed and distance from the home barometric altitude. It is easy fooled by barometer drift, so it could indeed fire up your throttle.
I would highly recommend that before you pick your plane up you disconnect the battery. Also, always approach the plane from an angle where you will not be hurt if the motor starts.