One of the cases cited in the Divisional Court's judgement (which went the government's way -- the Establishment clearly isn't united on this, is it?), by the way, was R (McClean) v. First Secretary of State, which concerned whether or not the confidence and supply arrangement with the DUP, and particularly the £1 billion extra funding for Northern Ireland that went with it, was lawful. It clearly was, of course -- but my main point is that one of the Judges in that case, who then emphatically sided with the government in no uncertain terms, was a certain Lord Sales:
// In my view [the idea that the government had an illegitimate
conflict of interest when entering the confidence and supply agreement] is not remotely arguable as a contention of law. In this political context there is no relevant standard of impartiality or disinterestedness which has been breached. The confidence and supply agreement is a political agreement ... The law does not super-impose additional standards which would make the political process unworkable. //
He could hardly be more clear then: judges won't step into matters of pure politics. They will step in when the government breaks the law. They have found that, in this case, the government acted unlawfully. What is so hard to accept about that?