That’s not a “buff” that’s literally a bug fix. Bonegrinder doesn’t say “When you consume KM with Obliterate” it just says “When you consume KM”.
And “fixing” DND cleave to work better with the legendary dot is a waste of resources. That would basically require and entire revamp of how cleaving works under the hood to prioritize targets without the dot. Complete waste of time and energy just so Frost DK and only Frost can get a single extra dot when Obliterate is used.