Knowing how government work it would not surprise me at all to read that each airport now has TSA officers with SWAT training and they have all kinds of weaponry stashed in a locker somewhere.
Give it a few years, they will be.
Less an institutional approach to security, more an example of institutional panic.
The NG is fine with passing out guns - they probably break them out one weekend a month and dust them off.[1] But passing out ammo - that's a serious step. Some officers freak the heck out when they think about troops having actual live bullets in their magazines.
In the 1980s era Marines, on barracks duty, I actually rolled out to a for-real no-kidding 'we're being shot at' incident with a rifle, a radio, a flashlight and no ammunition.
The reasons _why_ are complicated (and this isn't the place for a sea story) but it boils down to 'the troops weren't trusted with bullets - they might shoot someone'.
[1] I understand this has changed, for the better, since 9/11. Now they break them out and _clean_ them on drill weekend.