I have no love for Movistar, but it is reasonable to think that Mas is in a battle for a podium place with Carapaz, so isn't that why they were riding?
In the third week, you'd defend your position, but on the first Friday of the race when you've got the race favourite's team on the ropes? For what benefit? Mas isn't going to win the Tour, and is an outside chance for the podium, so why waste your team so early.
I have no love for Movistar, but it is reasonable to think that Mas is in a battle for a podium place with Carapaz, so isn't that why they were riding?