I guess in order to be prosecuted for inappropriate use, someone would have to file charges. If I were a SAR guy, and you just made my job a whole lot easier (by broadcasting your coordinates with a PLB), I probably wouldn't be all that mad that you were "just" lost and not actually facing imminent death.
Also, say you're lost but not seriously injured. You wait to activate your PLB. Three days goes by. After three days, you're weak, severely dehydrated, and semi-incoherent. Now, you really are in a pickle, and you activate your PLB. It's going to be a lot harder to evacuate a person under such circumstances than it would have been if the person had simply activated the PLB in the first place. I think the case can be made that if you're truly lost, a life threatening situation could in fact be imminent and PLB activation therefore justified. Of course, you wouldn't activate a PLB the first time you went around a turn and things seemed unfamiliar.
HJ
