Oh I got all the facts wrong, I meant Hakusensha... but yeah I can't really make sense of their writing process and creative decisions. I've seen better continuations than whatever they're trying to do here.
This is speculation from my part but I think he was probably forced into that "consultant position" by the higher ups at Studio Gaga. From the way he talks, it doesn't seem like he ever wanted to be involved in the project. Weren't they the ones who approached him first?
Studio Gaga probably just used his name to slap legitimacy onto the "continuation" because he was... Miura's best friend! And he's an established mangaka! But he's not actually working on the continuation. It's just a glorified consultant position. He seems to be stern about not adding anything...