>>55538368this is certainly a reason but also there is the fact that Masters is a third party, so probably their license is only limited to the mainline games published by GF (Satoshi being there was probably a TPC's mandate to promote the series finale)
I suppose there would be less problems if the game was made by Creatures or GF itself, because iirc Bandai once said that everything that happens in a spin-off has to be approved by TPC and the producer of Pokken specified that even though Shadow Mewtwo was made by their designers they had to ask permession to make it and they'll have to ask permession if they want to use it again, so probably something changed with how the rights are located within the company.