There's no sign that he is lacking in incentive/incompetent/lack of experience, in fact, he mentions that he is actively making it known to his teammates that he has spare time and is not loaded during meetings.
He hasn't mentioned any struggles to deliver or challenges with his past tasks; it just comes across that he is much less busy than his peers and he is wondering why. Maybe he is not liked and that's why I mention freezing him out, I guess one can classify that as a "communication issue" or the other possibility is that it just takes time to be integrated in a big company like other commentators have said.
By freezing-out, I don't mean that his teammates are actively hostile against him but just that maybe they don't trust him yet to give more tasks, just like how any newcomer is treated with some unfamiliarity at the start. I guess that counts as a "communication issue".
You seem to like to point the blame at the employee only while others have mentioned that it just takes time to build trust and to be given tasks and others have mentioned that he might have already lost the trust of his teammates which I guess does point to a failing in his part if so.
In a big company, there is also usually more room to coast and that is another possibility in that the manager is just not pushing that much and that is normal for a new-hire. I think there are just more possibilities than the fact that the employee is incompetent which seems to be your immediate conclusion without sufficient evidence.