If Slackware's coreutils package gets an upgrade, there are a couple of possibilities:

(1) Pat uses this patch (there is also a patch for the new coreutils that was released last month) and you just use upgradepkg to get the new package installed;

or,

(2) Pat does not use the patch. As he told me, he is not particularly fond of patching coreutils; his view is that when the coreutils developer team would think it was important, they would fix it themselves.
In that case, you will have to apply the patch again when Slackware's coreutils is upgraded and you get the "unknown unknown" back...

In any case, I very much doubt that a future upgrade of Slackware's coreutils package will have tools that suddenly start complaining about "obsolete options"!

Also, if Pat releases a new package, it will most probably be the new release with a higher version number. In that case, "upgradepkg" will remove my package and install Slackware's.

Eric