The fact of the matter remains, even if one person loses two characters due to accidently pressing Qy, it is one too many. It is your own clumsiness, yes, but you do not deserve to be punished for such an error. In my opinion. The times I have pressed Q instead of S was after long sessions, I made a conscious decision that I'm going to make mistakes if I continue playing further. So, I decide to save, but I'm knackered and indeed make a fatal error. Not fair man.
I also like the idea Porkman supplied.