Sure, it can be used as money (assuming what authors say is correct). Virtually any physical items that are hard to fake can be used as money, as long as people believe it's worth something. And if we are okay with complicated and rather expensive manufacturing process (since Kong isn't something you find in the forest), it really is a non-problem to create a new "government-independent currency", print it and sell it. Nobody really gives a fuck about that, because money is worthless unless you can spend it. And as long as Costco doesn't accept Kong (or any other made-up currency), it would be hard for you to spend it on anything other than unique hand-crafted chairs or cocaine. And it would be hard for them to start accepting Kong notes, while being a government-compliant entity that pays taxes, as every physical bill they get must be accounted for and put into a cashier machine.
And, by the way, since every Kong bill is unique, it isn't any more anonymous than dollar bills: i.e. pretty much anonymous as long as they change hands without touching real cashier machines or ATMs, which, as it happens, is not so long, because people don't generally exchange unique hand-crafted chairs for cocaine, they buy/sell it, then go to Costco to get some more conventional goods or services.