He says it could be wrong in not those words, but I think Snopes is more about rumors. Besides, why didn't they offer a counter-argument? If they know it's not a mini-catechism, did their source not say what it was about?
crivoice.org/cy12days.html This offered more of what else it could have been. Though Wesleyan, I think, it says it could have been a clandestine catechism.