Sure, that would be a little different, but unless you could make a convincing argument, backed up with a solid set of unit tests, at the least, as to why and how you were able to remove that much code whilst only adding a comparatively small amount, I’d still be inclined to reject it and ask for it to be broken down into smaller units.

Now, that explaination might be something along the lines of it being dead code that is not called from anywhere, or even that it was a patched version of an upstream library, and the patch is now included in that upstream, in which case, fair enough, good work, and thanks very much. As a rewrite or refactor though, it’s too big to sensibly review and needs breaking down into separate features.