I think we both think the other's objective is fair enough.

you should probably have made it more clear in the Less Wrong post that you were trying to enforce this norm

I probably should have made it clear, but I'd also like to encourage the norm that with or without such explicit per-post policies, where someone makes a post focussing on counterargument A, that commenting about counterargument B is recognised as logical rudeness. This doesn't help with the bind you find yourself in today, but might help in future.