TSA (more accurately - CBP, more generally - DHS) contract out the hard engineering to Cellebrite and NSO Group. Those companies develop a dumb-proof box. The CBP agents at the border take the phones, plug them to the box, press a few buttons, and that’s it.

No one in the TSA/CBP/ICE/DHS needs to be smart for this, that’s the job of private engineering firms/contractors.