Wil also comments in the thread about Amazon strong-arming him, "Amazon will disable Delicious Library if I re-release my iOS viewer app right now. They have told me this explicitly. I don't think it'd help you any if I release an iOS viewer and then immediately am forced to pull it and Delicious Library from the stores."
Wil Shipley explains why Delicious Library 3 doesn't have sync and ends with, "The simple truth is that at 3 1⁄2 stars we will run out of money in a year. At 4 1⁄2 stars we stay in business. That's the ominous reality that tiny shops like ours work under."