Isn't airline safety the reason the glaser safety bullet was developed?Yes, I believe that was the main reason those "safety bullets" were developed.
However, the main danger in an aircraft isn't shooting out the side of the fuselage or shooting out a window. The main danger is shooting through the interior dividers and hitting an unintended target.
Small bullet holes in the outer walls of the passenger cabin would not be a serious problem. The windows of most airliners are made of a polycarbonate material (Lexan™ or an equivalent). They don't shatter, and they are somewhat bullet proof. Even if a bullet penetrates a window, it will only make a small hole. The way the cabin pressurization works on most airliners, you would have to take out a couple of entire windows before the pressure will fall off in the passenger cabin. Of course, if an entire window comes out, there's going to be a very strong wind sucking things out the window hole. But on most airliners, the cabin pressure system could pump enough air in (and through) to maintain pressure even with one entire window out. Small bullet holes would be inconsequential.