If the copy becomes distracting in the design then you are doing something wrong or they are discussing copy changes. It might be a bit annoying but you could tell them that that discussion would be suited.

At worst the discussion is at least working towards the final goal of your site where questions about lorem ipsum don’t. ypographers of yore didn't come up with the concept of dummy copy because people thought.

Just fill up a page with draft copy about the client’s business and they will actually read it and comment on it. They will be drawn to it, fiercely. Do it the wrong way and draft copy can derail your design review.