Yah yah, the anti-gun nuts said the same thing and continue to imply the same thing to this very day about polymer guns like Glocks, even after the National Academy of Sciences, NASA, and the FAA definitively proved that polymer frames were moderately radio-opaque and can easily be identified on X-rays.
You could conceivably construct a small caliber gun with extremely limited capacity that would be useful for shooting one or two persons but would not be able to puncture the skin or take-down a commercial airliner. IOW, there are a lot better ways to inflict a lot more damage or produce higher body counts than smuggling a gun onto plane.
Particularly after 9/11, people just aren't going to let anyone hijack a plane anymore, even if it means taking a risk to themselves in order to subdue the person.