I don't think you were flippant at all. I just think that Rioch and Gemmill showed they weren't past it against Holland. Rioch and Masson did decline quickly after that World Cup, but Gemmill was made captain of Scotland for about another two or three years, including a season in which he was helping Nottingham Forest towards winning the European Cup, as you say.
BTW / Masson's 75 minutes in Argentina would be explained by his poor performance against Peru and then his mad idea of claiming he had taken the same Reactivan as Willy Johnston, even though apparently it wasn't true but he wanted to show solidarity with a mate, which meant that the SFA & McLeod could never have contemplated him playing again.
What is baffling was how our playmaker, Masson, was not replaced by our other playmaker, Souness, for the Iran game. McLeod's single worst decision, of quite a lot of bad ones, in that tournament.