I’m thinking maybe it’s not actually talking about Shanks? He doesn’t say catch up with old friends, but when old friends. Of course, that’s nitpicking a translation, which isn’t always a good idea.
Say, Shanks is already on Elbaf.
Then Dorry and Broggy show up, and all the locals of Elbaf thought they were dead because they’ve been gone for a hundred years.
Big party to celebrate, Shanks stays because he likes parties and he likes to see “when old friends who thought each other dead are reunited.” Meaning the people of Warland and Dorry/Broggy.