Personally, I'm objecting to your approach of "here are my terms of conversation, and they are supremely reasonable".

May I then refer you something stated in the OP

Also, if you have any problems with the assumptions I proposed, let me know, so that we can agree on a presumed model, and work from there.

Regards,

supe

The OP states directly that if you have an issue with any of the assumptions made then state that and add why so you two can collaboratively define a model. Your accusation that the OP is MAKING you argue on their terms is simply false. So, therefore the most logical following question is: What issues do you have with the assumptions and/or structure in the OP's argument?