Right, but I am just thinking about how we specify in .hgeols what the repository is expected to be as this extension might work out nicely for other projects who prefer CLRF as their repo-native line ending.
This is what I refer to as YAGNI. Subversion has LF as the internal storage, and, IIRC, so does CVS. I don't think there is any precedence for wanting something else - and frankly, I can't see how repository storage would matter.
You are mostly right that the committer name would be the same (except when the committer was pushing some changes pulled from the actual contributor), however, I still see these whitespace-only changes as a complication.
It's unfortunate, but I see it as a rare occurrence as it would only happen if someone got sloppy. And it should typically get caught client-side before the commit ever occurs, minimizing the whitespace-only commits even more.
It would, of course, be possible to ban them altogether, at the expense of users having to replay changes.