The implication is that, in the past, such a meeting would be fine, because they're an expert in what they've authored. It's "hey can you join for 5 minutes" because, in the past, they'd have had deep knowledge off the top of their head of the things they'd committed under their name.

But now they're not an expert in the code they've recently committed.

Maybe that's OK and expectations need to change, but I'd bet there are a lot of cases where the organization really wants to produce a (code, expert-in-the-code) pair, and should be willing to pay a little time to do that over producing just (code, guy-who-prompted-it).