That's contradictory to the evidence provided in the piece. Miyamoto was given a directive by Iwata to sell the gamepad. With his credentials. Make a few games that people cannot ignore using the Miyamoto magic and Miyamoto brand. Miyamoto actually did PR for SFZ. He stuck his neck out for SF, Guard and Giant Robot. Intentionally and publicly.
Iwata and Miyamoto were both at the forefront of electing the GamePad as the sell feature of the Wii U. So they both had a vested interest in proving the design choice was somehow beneficial or important game design.