I feel you are seeking any justification and accomodation for ploughing on with a local experiment to get rid of Conservatism which has ended up in aiding to entrench it.
I don't understand this. Are you referring to the SNP? If so, that seems a false argument to me. The SNP would be able to vote with the Labour party if they felt it necessary on any given issue to attempt to defeat the government. If the numbers were right they could form some kind of alliance. Unlikely I realise, but still possible.
Surely quite often politics is local in nature. Be it local to Scotland, N.Ireland, England, Wales or the regions.
I don't see any attempt at justifiying a local experiment by rightly criticizing worrying aspects within the Labour party. The two simply are not linked.
Your argument sounds profoundly undemocratic to me. Although, admittedly I may have misunderstood your poorly worded post.