I don't believe they have published any details on how they plan to enforce this - only that the are serious about it.
They may simply rely on the UDPR, letting the complainant fund the research, and using their policy as the reason to revoke the registration.
This does not make complete sense to me though, since in the dropped domain scenario, the UDRP complainant would not have any better chance at picking up the domain than anyone else.
Now if they gave the domain to the winner of the UDRP suit, that might start a whole rash of complaints over registrations that don't meet Nexus requirements.
It will be interesting to follow. I wonder what CIRA does now for .ca domains?
-t