Since they are legal items that are merely prohibited to transport through the checkpoint, and since no forefeiture action has been taken which would lawfully deprive the owner of title, only a seizure of possession to prevent the prohibited action, they should be held for return to the owner outside of the secured area with storage charge (and shipment charge if an option for remote return is provided) covering reasonable actual costs only.
Anything else would seem to be deprivation of property without due process and taking for public use without just compensation, in violation of both the due process and takings clauses of the 5th Amendment.
The owner is given the option to either go put it back in their car, ship it to themselves for a small fee, or let the TSA take it. It's not like "hey, you screwed up and now you lose this item for good!"
“small” fee my ass. When the TSA confiscated a camping knife I kept in my backpack and forgot about, the agent said it’s about $20. Also, for someone who boards in 30 minutes with a TSA line just as long, they don’t really have a choice: it’s lose the item, or miss your flight. So I had to let them take it.
Anything else would seem to be deprivation of property without due process and taking for public use without just compensation, in violation of both the due process and takings clauses of the 5th Amendment.