Hardly. I don't buy that for a second... if you're talking about "legally", then I think once you report it stolen, then you're off the hook.
If you're talking about morally, meaning a criminal is now running around with a gun you somehow were negligent enough to let them obtain, I think that's a stretch, too.
I bought a knife a couple years back that had a "glass breaker" stud on the back of it. Actually some very similar knives are being sold right now in the classies... interestingly, in all my years in emergency services, only twice have I ever had the need to break a window myself. Once I tried a rock, a screwdriver, everything I could find, and couldn't find anything to help get the guy out of the car. The second time was on my wife's car, when I was trying to get it towed away to a salvage yard for scrap and she had given me the wrong key... I tried the "glass breaker" on the back of that knife and I beat that thing till my damn arm was sore, all it did was blunt the metal stud and scratch the windows.
What a POS. lol
Yeah, if the glass-breaker isn't made of at least a semi-hard high-carbon steel (preferably Carbide), it's probably not worth it (the ones with an AUS-8 "glass-breaker" are ridiculous). Even with a Carbide or harder carbon-steel glass-breaker, it's a pain in the ass to really break a window (especially a side-window rolled up in the sealed frame - lot of shock absorption going on there).