How to answer a reviewer asking for the methodology code of the paper?
You cannot answer “convincingly”, because your assumption that it is okay not to provide the code is incorrect, and the reviewer is correct to ask for it. And the fact that it’s time-consuming to prepare the code for release is neither here nor there: it’s also time-consuming to write a good paper and polish it over and over to make it into something people can read and understand; but that’s what good researchers do, because they understand it’s important and that this is the way to do good science.
For a related discussion, see here.