I know we've done this subject to death, but I've been trying to get some facts straight in my own head.
First, one cannot assert any intellectual property rights over facts - items of information. Once you have published such facts they are in the public domain. Rights only come into it when you do something original with those facts.
Copyright can only be claimed over original text or images, in hard copy or digital form. The information we use for family history - BMDs, census data, parish register entries, MIs - is, once published, in the public domain. We are breaching copyright only if we reproduce the publication or portion of it. Organisations or individuals may acquire data from the original source and publish it, possibly in a searchable form, for payment. Once someone has paid to access that information, it is out of the control of the publisher. I would be interested to know of any legal action which contradicts this.
Terms and Conditions are another matter. Generally they assert, quite reasonably, that you must not use the information for commercial purposes, and if you've agreed to those T&Cs, you would probably lose the case if anybody took it to court.
Where does that leave the problem I started with - the decision that I can't offer to look in the booklets of early directories that I have purchased and pass on any relevant information? I know the answer to that question.