It should be a clue that it was not an RF problem because the other servos were not affected.
I can't say why the kill switch caused the problem. There is not enough information there to analyze it.
My guess is there was a coupling thru the power supply. There is some problem with the kill sw. that overloaded the power source. But I don't know. I have no information on the kill sw.
Keep in mind when you write to the manufacturer you usually don't get an answer from the technical people. Some tech writer usually answers your letter.
If you would like to know how SS works and why a resister in the spark plug stops RF PM me and I will write an explanation. I have been out of school to long to explain it mathematically so I have just tell my impression so it wont be hard to understand.