I always assumed he had insiders from the show, and others in the know. Folks from previous seasons tend to get information (most likely from their contacts with ABC employees). We know RS isn’t the only one that is provided with spoilers – posters on this board have sources of their own who seem to be legit. It’s likely a mixture of insiders, past contestants (maybe) and everyday folks who have access to the information. Remember how SDL used to give us information and he once said that RS wasn’t his source, but that they did share some sources.