A subscriber who signs up for a tournament is allowed to continue with it even if he ceases to be a subscriber. Same goes with clan games. It can take a couple of years to complete a tournament so there are probably quite a few non-subscribers in that situation.
16932 looks like one of those rare animals that Russ used to produce occasionally - a nonsubs tournament - the idea being that people who tried it might like it and sign up to get more. Haven't seen one of them for years.