The author should absolutely do what he wants, there is no problem with that, and I don't claim entitlement to anything beyond what I paid for. The only problem I have is with lack of a minimal status update. I don't expect blogs, emails, honestly not even support from the author. Only a tweet "I'm taking a break for now, will continue when feel better." This is what Ryan Bates did with railscasts, and I respect that. Then again, I don't even claim entitlement to this type of tweet, it just would be a decent thing to do. Saying nothing signals abandonment, while "I'm taking time off" signals exactly what it says.