I know; North got confused by the bidding, because South must have three diamonds (and must have chosen a non-standard lead), but this is one of those situations that would be covered by the general rules we've talked about for playing high or playing low.
And, it appears to be the case that "XX implies no fit" means 4-♣, so I presume 2NT Truscott/Jordan would show 5+♣. Why should this be different than showing support vs not if the opponent had passed? Direct raises of minors should always show 5+.