Gemtasu did an inteview with Kamiya, he said this.
Kamiya: “We felt it did not quite reach the audience that it deserved. As creators we are very confident in the game. This project is a unique opportunity to bring the fans together and see how far the game can go, which is why we went the crowdfunding route. We did speak with Nintendo about it initially, but they said, ‘you either do it only with us or do it yourselves.’ But speaking with them they allowed us to cut a deal, so we took upon ourselves to start this project. Dangen Entertainment is helping us. We have seen successful campaigns in the past, Bloodstained in particular, so we saw it as a very unique and interesting opportunity.”
Seems like Nintendo was willing to let them do this without giving up the rights as long as Platinum got the funding together themselves. I do believe that this shows how highly Nintendo and Platinum value their relationship with each other. Should be interesting to see what this means for the IP going forward, because as you said this might show how little Nintendo values the IP or maybe it gets strong enough sales that Nintendo might fund a sequel.
That's intriguing. I'd totally like to know what was put at stake in that deal regarding the rights and/or publishing. I doubt Platinum will ever disclose the details, though (unless they haven't done so already), let alone Nintendo.