They have no other arguments any longer. The only remaining talking point they have is that if we raise the block size limit too much that it will result in centralization (without a clear definition for what this means).
So we don't have 1% orphan rates at 1MB blocks? So the orphan rates would not grow if we had e.g. 8 MB blocks right now? It really seems like they don't really have any arguments. You should really discuss this with
other people (not if you're going to be closed-minded) before making slides that are incorrect (hint: Luke-Jr said something about one on IRC if I recall correctly).
fear of being proven wrong.
They're not wrong. Centralization is already a problem.
Can you ever conduct an honest argument? Seeing as the answer is no, I will suggest a solution: stop talking
I suggest a better solution. Just put him on ignore and you will have a better experience around here.