I explained in some detail why "I think the blogpost is sensible" is not the same thing as "I think this particular thing that the blogpost argues might be a good idea is a sensible thing".
Your response is to ignore all of that and just reiterate "you said the blogpost was sensible, therefore you think this particular thing is sensible". The very thing I had just been explaining that I think is an error.
I am not sure whether you're not reading what I write, or unable to understand what I write (presumably, if so, not out of sheer mental incapacity but because politics makes idiots of us all), or deliberately misrepresenting what I write, but whether it's any of those or some other thing I haven't thought of it's making it seem increasingly unlikely that any actual fruitful discussion is possible.
> It was the only actual point you made
Of course this is utterly false, not least because your description of my "long rant" (a characterization that obviously I dispute, but no matter) you mention several other points I made. I assume you mean something like "the only point you made that I consider relevant", in which case we have different views of what is relevant.
> how the law doesn't define cousin incest as incest (this has no bearing on whether cousin incest should be illegal)
It has bearing on whether or not it is reasonable to do as you have been doing and simply call it "incest" on every occasion, thus turning "I think a blogpost arguing that first-cousin marriage should not necessarily be made illegal was, on the whole quite sensible" into "you think allowing incest is sensible".
> that cousin incest is legal right now (which has no bearing on whether it should be illegal in the future)
It has bearing on whether or not it is reasonable to do as you have been doing and write about suggestions that the thing not be made illegal as if they were suggesting that the thing be made legal. Those are quite different things: just as we don't try to make every bad thing illegal because making things illegal has costs, we also don't try to reverse every bad law because changing the law has costs.
> that it was the political right that pointed out the horrifying article
Oh, come on. I mentioned that the article was retracted soon after it was published (which is obviously relevant since you were trying to cite it as somehow representative of official attitudes in the UK). It seemed relevant why it was retracted, so I gave an eight-word summary of why. And now you purport to list the topics of my "long rant", and one of the three things you mention is the fact that that incidental eight-word summary included the words "right-wing".
If you don't like it that my comments are devoting space to complaining about your dishonest rhetoric, then perhaps you should use less dishonest rhetoric. If instead of "the NHS Genomic Education Programme proposing that incest not be illegal" you had written "a post on the NHS Genomic Education Programme's blog exploring arguments for and against making first-cousin marriage illegal, and evidently leaning toward not making it illegal" -- which is the nearest not-actively-misleading thing I can come up with to what you wrote -- then I wouldn't have had to say any of those things you complained about.
Of course, if you'd written the honest version rather than the dishonest version then it would have been obvious that it didn't give much support for your attempt to represent immigrants in the UK as "the worst people", so I guess that was never really an option.