Received a PM.
I cannot see any reason why "much... than" would be universally incorrect. For example, following sentence is correct:
James was much more appreciated outside his home than he was inside it.Same with "much.. that". In fact, following is an officially correct sentence:
However much United States voters may agree that there is a waste in government and that the government as a whole spends beyond its means, it is difficult to find broad support for a movement towards a minimal state.
However, it would perhaps make a more meaningful conversation, if you could cite some official sentence using this construct that we can use as a basis for further discussion.