Joseph has to give that some honest thought. How much does he want to know? If everyone from home knows him as an old man, maybe he should have some information to work with... but on the other hand, he's already starting to get the feeling that he won't like what he hears.

"Maybe it's best to hear it from- Jotaro, was his name, right? I mean... he would know me best, out of the three of you."

He does file away the knowledge that Jotaro might have been depressed. Or might still be. He knows the word, although he can't say he has much experience with it. Definitely not something to bring up during a first meeting, but it might be a good thing to prod at some point.