Taking a persons property and destroying it, because you suspect its counterfeit?
!!!! That could get you in a lot of trouble !!!!
I'd recommend taking the deck as part of any deck check, photographing the suspected cards, asking the player about the cards, and where he got them. Advising the player that you think they are counterfeit, and asking him to let you send them in to UDE, including his name address and UDE number, so that the cards can be returned to him if you are wrong.
Just my thoughts....