"New Judge is similar in that he constantly says things along the lines of, "I couldn't care less what Scotland does", but never, ever, fails to contribute to threads which are specifically about what Scotland may or may not do!"
I contribute to lots of questions where the main topic is not of particular interest to me, QM. As far as this particular topic goes, I have generally no interest in what Scotland decides to do with its devolved powers provided it does not impinge on the rest of the UK and principally England (where I live). This particular proposal will because to remain in the single market Scotland would have to agree to freedom of movement. Quite how we can have fundamentally different immigration regime in one part of the UK to the rest is somewhat of a puzzle which I don't think has been particularly well though through by Ms Sturgeon and her chums.