Why would any club or player tie themselves into a binding contract before they could be officially registered.No he can sign a binding contract with the club , which is far from meaningless, he can train, he can work with any medical and physio staff. The only thing he can’t do until the registration (not transfer) window opens is play.
Are you telling me City or any other club would leave themselves open to losing 64000000 pounds, if something went tits up , before he was officially registered.
As you say he can't play until the registration window opens, which also happens to be on the same day as the transfer window opens,which is what we will be doing when we complete his transfer/registration from his present club.