It would be simple for the honest TSAer to write his/her name on the card, just as it would be simple for the dishonest TSAer (c.f. those who sell other people's cameras on e-Bay) to write someone else's name on the card, or a random squiggle, or say "someone else put my name on this card" or "forget" to write their name or "forget" to put the card in that bag that had the camera or ...

And even with a name on the card, TSA can still say "the baggage handlers did it" and the airline can still say "TSA did it" and there's no resolution.

Let the pax lock bags properly and inspect bags with the pax present. This would mean rearranging a lot of airports, but just do it! In (rare) cases where that's truly not possible, install proper security cameras, actually turned on, and make the recordings available when there's a complaint.