Last year he was treating it like one of his shows or national 'experiments', right until around spring when it was meant to open, and then if I remember he made a small flippant remark on Twitter when it did actually open "after all the delays of a real train service" or something.
It's obvious he lost personal enthusiasm when he saw what had been created under his name. Not saying he doesn't have interest in it, he will at least have business interest in it and want his say to help improve it. I'm sure when the new version opens, he'll do his share of promotion for it.
But really this is all Merlin's project (/mess?) now - with Derren as an IP only. Kind of embarrassing when they had to get a hammy actor in an anagram name to replace him for the video promo...