It could well be that the team management would prefer for him to drop and concentrate on training for the next race rather than wasting himself in a less than productive way. Why get a potential for some mediocre support and risk over-training, crashing, the wrong type of training etc which could hurt him in the sprinting stages in the TdF or other races.

In my mind, there is nothing wrong with a specialist specializing.

EDIT: Also, he is still young, he could round out his abilities with time...