I think the story of how it was unearthed was the guy's family business was buying junk in bulk from closing businesses, and his dad had got the Nintendo Playstation in a lot of office cafeteria furniture or some shit and had it just sitting in storage.
I think you are confusing this with something else. The Nintendo Playstation came from the son of a former Sony executive who kept the thing as a work momento.
Other big proto finds were the Nick Arcade Sonic 1 build and the mid-development Duck Tales build.
It was a weird Miyamoto mandate IIRC, kind of like no story in Paper Mario and don't make an F-Zero until we have a dedicated controller for it. (okay that last one wasn't a mandate but just a stupid thing he said)
I also think it may have had something to do with Jet Force Gemini not meeting sales projections or something, although I think that game probably would have been better suited for Star Fox tbqh
It wasn't a mandate, Nintendo couldn't
mandate anything since they only owned 49 percent of Rare. It was a recommendation in an era when people didn't know well enough to not always take Miyamoto's advice. They could have said no, like the Goldeneye/PD team did when Nintendo recommended they have all of the characters shake hands and be friends at the end.
However, having said that, there were a lot of reasons to actually take Miyamoto's advice, setting aside his reputation and Nintendo's clout as minority owner and publisher. Star Fox was a big IP that had a good reputation and always sold a million units back when that meant you were a hit. The foxes in DP did look a lot like Star Fox characters, being two legged walking foxes in an era when there were only so many ways to portray a two legged walking fox in a video game. The N64 was viewed as less successful than need have been, with the Dolphon/GCN being full of promise. DP was shaping up to be a massive game, which meant more expensive carts with bigger boards and possible mandating of a memory pack, aka it would have cost more to product than even normal cart games (with potential limited audience) versus being put on a normal GCN mini-disc. The N64 was nearing the end of its life and game sales were declining (compare the sales of, for example BK vs BT or GE vs PD, JFG versus BC or KI:G, etc.) There were a whole lot of reasons to port the game and change the IP. We ended up the poorer for it, but on the other hand got a good deal on them reworking Conker*, got a much better version of Banjo Kazooie than we ever would have on SNES, got a much better version of Animal Crossing, etc.
