"Would you care to publish this? Sincerely, Robert B. Parker"

Robert B. Parker is asking if the recipient of the quote would have an interest in releasing whatever it is he has written. He is expressing his interest in having his work released and is being respectful and considerate in his demand. He is likewise being genuine in his demand, as evidenced by the closing of his quote, "Sincerely, Robert B. Parker". This shows that he is major about his request and is expecting a positive reaction. It is most likely that he has put a great deal of effort into whatever it is he has actually written and is now looking for somebody to publish it. He is confident in his work and is hoping that the recipient of the quote will be interested in publishing it.