For me it is not an absolute indication of what is right and wrong, but the presence on the list of things that all would agree are wrong means that it is not fair to dismiss the list as being things that are now never wrong. This is how Blackstone's argument comes across.

Is it how it comes across, or is it how you want it to come across? I never made such claims. I made the, factually correct, claim that unless you believe everything on that list is still forbidden, you are picking and choosing which parts to believe and which to discard if you use the presence of something on that list as a basis for proving it is forbidden.

The alternative isn't to believe that the opposite is true and none of it is forbidden, that wouldn't make much sense at all. The alternative is to accept that the list no longer applies to us and the presence of something on that list is not indicative one way or the other of its current status as forbidden. The presence of incest on that list is no more indicative of its current forbidden status than the presence of trimming your beard.