If this degenerate did steal the cards, would have been better to continually spray him with a hose or throw paint on him. The paint would be non-toxic and would specifically be for these types of situations.
He should then be forced to stand in the middle of the convention wearing a billboard sign that states he is a thief. People should be permitted to throw tomatoes, fish, and cabbages at him. Afterwards, he should be forced to clean the bathrooms with a toothbrush and empty all the trash bins.
So many more serious crimes out there that would benefit from the effort these cops showed with him.