Two things.
1. If you perform with a wallet you'll be surprised how often people do not want to inspect it. Wallets are incredibly personal and valuable items in most situations I find myself in it would be very impolite to inspect someone's wallet.
2. That said, your audience could look over this casually. There's not really anything to see unless they spend a bit of time with the wallet.
So, it can be looked at closely. In fact, it can be looked at much more than most gimmicked wallets. If it is inspected though you will run the risk of them finding out the wallets secret workings.
Finally, the routines that you are taught do a good job of making the wallet seem inconsequential. As far as your audience is concerned, you will be reading the spectator's thoughts while their word is in the wallet sandwiched between 2 credit cards, inside a wallet inside their hands.