“Was he leaving the country? If not then it is none of their business what he is carrying and how much.”
If he was trying to leave the country, they would have arrested him for not declaring it (since it is over $10,000). So, what exactly, was the basis for taking the money? Maybe they felt he shouldn’t carry so much?
There is no law against it but you might be doing something illegal.
Maybe you are. Maybe you are not. But either way it is no reason to detain someone or take their property.
he did not declare all of it..
They took the money as it was unclaimed. The suspect refused to sign "a receipt for the secured currency and left the building, walking away from the money. "
This is not a case of asset forfeiture.