I did forget one possibility.

The entire charade is set up for TSA revenue protection!

When visitors want to go through screening to see their loved ones or unaccompanied minor to the gate safely, they aren't PAYING THE TSA their tribute .... I mean the $2.50 per segment fee. This is probably seen as providing a service for nothing, so they trumped up the lie that it's a security issue to have too many people on the air side.

Too many visitors means revenue lossage to the TSA.

Too damn bad, TSA.

You already get double fees without doing extra work on connecting flights, where most passengers pay two fees and only pass through ONE checkpoint.

Greedy bastids.