It wouldn't be a bad idea.  Of course, you'd also need to update Tools/script/diff.py.  Tests should be added as well, since we have started adding tests for things in Tools.   The tests should be written first, to make sure that the behavior of 'diff' does not change, since I know there are people actively using it (on Windows).

I think it would also be a good idea to change the docs so that the actual diff script is embedded in the docs (sphinx has a directive for doing that), rather that duplicating the code.