Considering that triggering it requires unscrewing the end caps and pulling out the +/- 70 cm antenna wires (1/4 wavelength of 121.5 MHz) to create the dipole, I don't think "triggering by mistake" is a risk factor here. (Although "triggering while drunk" or "triggering by drunk friend" could be an issue.)
The bigger issue is that the rescue services/satellites are not routinely monitoring 121.5 anymore. So you're at the mercy of an accidently passing over airliner which happens to have 121.5 standby. And they typically don't have homing equipment.
You'd need the 406 MHz Breitling (which doesn't exist,
AFAIK) if you want a true PLB.
Personally if something goes bang the first thing I will be doing is putting out a Mayday to whichever service I'm speaking to giving my rough position, that will be enough to instagate a rescue. Any SAR chopper dispatched will be able to home into a signal on 121.5mhz no problem at all which is all I'm worried about.