The Esk seems to give the impression that World Heritage Status is optional and can be decided by the Council and Peel. Obviously, it is not. The government is under legal obligations to identify, protect, preserve all of its sites granted World Heritage Status. It really doesn't matter what Peel and The Council think or want. All planning applications for the area have to be agreed by Historic England, and if it doesn't agree, which it wouldn't if UNESCO had reservations, it advises the Secretary Of State for the Department for Digital, Culture, Media and Sport who will use his powers to call in the application and set up a public inquiry.
I have wondered whether UNESCO were concerned when they saw that image of the stadium as a bowl on the docks, lit up in blue, with Everton down the side. That would probably not be suitable, in their view. What would they prefer? I don't know. (Perhaps, a rectangular building as the facade and a brick or stone style finish vaguely reminiscent of a warehouse? It would fit in but not be very inspiring, but the interior could be quite different.)