While the casinos do have posted notices that the chips belong to them, the value they represent belongs to the possessor. If they are validly held, then the value belongs to the possessor.

If I go to casino Q, and 'buy' a $100 chip, the chip may still belong to the casino, however it serves as a promissory note assuring payment. THis may be obtained thru use of the chip, or cashing in the chip. If the casino refuses you the opportunity to bet the chip, or cash it in, then they forfeit any claim to the chip. That does not mean you forfeit any claim in the value of the chip.

If they followed the statutory requirements cancelling a chip, then the chip is no longer valid. But they likewise forfeit any claim on that chip. Otherwise what would stop a casino from laying claim to one (or more) of the chips that have such a high value within the hobby.

If they would accept the chip, they had no right to confiscate it with restitution. I would file a complaint with the Gaming Commission. If somebody says to you it was only X amount, who cares. Every one of these "here is how we catch cheaters and criminals in Vegas" shows makes a point of saying it doesn't matter how much.