Meaningless. Rosenstein isn’t required to be truthful with the President regarding this, and he could easily be using weasel words: saying the President isn’t a “target” does not mean the President isn’t the “subject” of the investigation. Make no mistake, the endgame is the same in either case—they’re hoping to prolong it at least until after midterms on the possibility that they can get a new D majority in the House to draft articles of impeachment.
Dem boomerangs have a tendency to hurt them more than the intended target.
It might be the one thing that assures they won’t get that majority.