The boarding from remote stands had been planned in for a long time, they wouldn't have gone to the expense of building the new bussing lounge of they didn't want it to be used.
MAN won't want to rest on their laurels getting the slots filled. The redevelopment has to pay off, that isn't going to happen if you turn airlines away due to the build.
As said, the terminal should be ok, it's just adding back in what was taken away, not over subscribing the stands they have.