Maybe there'd be a different result from security guards provided by shops in the Mall if the security guards, properly trained of course, were armed.
Poorly thought out idea smacking of immaturity and lack of experience.
If you are going to spend that amount of money on training and vetting , ( and increasing salaries commensurate with the responsibility I presume?) then you might as well just increase Fed Police numbers by 200 and have a rotating roster through the airports concerned.
If the ‘armed security guards’ are funded by private operations then you won’t achieve the goal of them being ‘properly trained’ as the financial imperative takes effect, ( I can read the Headlines now after someone gets shot for talking back at the x-ray machine and it isn’t de-escalated).
If they are federally funded they might as well be full time Police and utilise the economies of scale regarding training and vetting and firearm management etc. In addition they can benefit the nation in a multitude of other ways than just airport security.