There are various species of information theory. I by no means claim (see my prior post) that Richard Posner embraces all varieties of that theory. If Posner embraces information theory ("properly so-called"?) -- if Posner embraces information theory at all, he embraces a particular version of that theory. (A knowledgeable person has told me, for example, that Posner does not use Herbert Simon's version of this theory. Whether or not this is true, I don't know.)
I will do some research and post a further note later -- in a day or two, perhaps.