Thanks for the clarification. I do not know myself. But I have heard a lawyer say that if you buy then use coins as a payment system you might not be liable. 
Given there is no guidance, every accountant has their own opinion and technically none are wrong. Some accountants intend to file as currency, some as assets, some as manufactured stock. It's a decision between you are yours. If you got audited, it's unlikely going to cause a huge issue if you have tried to pay your taxes in good faith. Worst case, I imagine, is you might owe more based on what they decide.
This attorney (#3) thinks they are taxable. No doubt you could find one who believes it's a currency and therefore doesn't think that.