Huh!
The piece says that it trimmed the diameter of the earth around the middle.
A couple things:
- They don't say, but I think they mean that rock went down, displacing water that went up. This would move mass towards the center of the earth and have the effect that they state. Is that what they mean?
- In any case, this would speed up the spin of planet and shorten rather than lengthen the day. It would - counteract - (to some microscopic extent) the effect that this leap-second is designed to repair.