Quibble over word choices however you want; my point remains. When you've got things like money and IP ownership involved, you need to have clear and consistent rules. If you change a set of rules after people have already agreed to them (which is already questionable) then you should at least...
It would be a lot less suspect if you'd had a list of exact changes and version histories to consult, considering there are things like money and IP ownership on the line. It's messy and unprofessional.
No, I'm a fairly successful RPG publisher/author myself and this contest is pretty awful all around. "Gets published" isn't any kind of real reward. (Especially when someone else is making all of the actual profit from your work.)
So you changed the rules after at least three people had...