He's saying that the older someone is the more their ideology defines them, which is itself probably inaccurate. And he says that that "could be a problem."
He's arguing about ideological stagnation. That's bad regardless of just about what the ideology is and whether you agree with the particular.
To quote Max Planck, "Science progresses one funeral at a time." That's as true of anything as it is of science.
Right, but that's different than saying he doesn't like old people because he disagrees with them.