Those dudes left Capcom presumably so they would have complete freedom over their games.
Creatively, i don't think Miyamoto's or Sakurai's views would clash with any of Platinum's guys' visions. They're pretty on the same wave or at least it looks that way for me.
Financially, though... Nintendo occasionally gets to be pretty cynical in terms of sequelisation, even more so than Capcom ever did. You might have some wiggle room though, like Sakurai who fed up with sequels at HAL left to do Meteos and Kid Icarus. Sakurai is a very special case though, with him being so close personally with NCL president.
Unless Platinum Games specifically requests to be part of Nintendo
Well, Kamiya DID beg to develop Star Fox a few years ago...