> And if we go by the assumptions that every possible state in this set of possible states is equally likely (a common assumption in classical probability theory)
I know I am being nitpicky, but despite the fact that yes, it's common to assume equal priors, this often has no basis---especially in regards to this question. With only one observation we know virtually nothing about the distribution of possible observations other than that the state that we observed is in a region with nonzero probability. We can't conclude anything else with any certainty at all.
I was happy to see that in the article the author discusses this point in particular.