Why not say "cellular telephones?" in the reg if there's proof they interfere. It seems to me the airline lobby was effective in having the regs crafted to allow them to force people to use the airlines airphones. But I'm a neocon, luddite conspiracist.
Well, I'm all for requiring people to turn off their cell phones on planes and on trains and in movie theaters anyway. But I just don't buy the "it'll knock the aircraft out of the sky" stuff.