I don’t think the Open Definition has anything to say about login requirements as a matter of access. Obviously a license that required a login to access would make the terms material were offered under non-open. But as a matter of access, the OD doesn’t even require open material to be online or gratis. I guess @rufuspollock feels differently but I don’t understand. I suppose this means the OD ought be clarified.
No idea when that might happen, this is a very slow moving project, which I think is appropriate. Nothing wrong with the census scoring taking OD compliance as necessary but not sufficient for the best score. Compliant doesn’t mean following-best-practices, and presumably the census wants to differentiate among providers doing the minimum and following all the best practices.