The reason for the transmitter controlled kill switch is a perfectly reasonable means of disabling an aircraft during any flight or ground activity. Any redundant system on these large scale aircraft make the hole hobby safer. If you are not holding your plane and the throttle sticks open and you can't chase it around. The only way you will stop it quickly is by a servo activated kill switch. Closing throttle doesn't do it quickly enough. Also having the fuselage mounted kill switch is redundant yes, but its safer. The AMA rules state you must have a kill switch on transmitter control to abide by the rules for magneto ignition systems. I also must say, Always, Always keep a fire extinguisher handy, also a AMA rule. And a good one. Fly safe and have tons of fun.