I'm not sure I would equate a pocket knife with a firearm. I always carry a knife because I bite my nails and can sometimes not even open a soda can. A small knife solves many daily issues with ease, from prying things, cutting things, trimming things, opening things, even screwing in small screws (like on glasses). I doubt many folks are considering packing 6 inch hunting knives, just practical folding knives.
Anyhoo, if it is really critical to get through metal scanners, there are many alternative material knives you can use from ceramic to Kevlar to plastic.
In the past I've had to check a pocket knife if it is detected. Given recent events I'm not sure what their policy will be.