I'm willing to give him (or anyone else going through this) a lot of grace here as I think almost everyone who will be impacted by AI will go through 3 major stages, at different rates with each step taking a while to both really be true, and then a bit longer to accept and solidify into reality. And our egos act as blinders on accepting that each next step after 1 is likely.

1) AI is useless.

2) AI helps me.

3) AI replaced me (unless I am a generationally gifted top performer in my field).

While he is, in fact, a generationally gifted top performer in his field, he knows that statistically speaking most of his students will not be which I think makes his apparent angst now understandable.