What does the reader learn from the stranger about his best friend Jimmy and what is his attitude towards this man in After Twenty Years?

When the policeman, who checks doorways on his beat finds a stranger standing in a store's door that used to belong to "Big Joe' Brady's restaurant, the man claims he is standing there as he waits to meet an old friend, who was a great friend, although somewhat of a "plodder."
This waiting man assures the policeman that everything is all right; he is just waiting for his old friend named Jimmy, with whom he dined twenty years ago. After this meal the friends parted, but they agreed to come back to their favorite restaurant in two decades after they had settled into their adult lives. While Jimmy was the truest of friends and they corresponded for a while, they had lost track of one another. The waiting man says that Jimmy was kind of a "plodder," but he has sought his fortune in the West, and because he was "hustling," and moving so much, he had lost track of Jimmy.

"But I know Jimmy will meet me here if he's alive, for he always was the truest, stanchest old chap in the world. He'll never forget. I came a thousand miles to stand in this door tonight, and it's worth it if my old partner turns up."

Clearly this man holds Jimmy in high regard, having traveled so far to reunite with his old friend. Even after he reads Jimmy's note, the man knows that Jimmy is still a true friend. For, he has not the heart to arrest 'Silky Bob' himself, although he knows that he must do his duty, too.