I don't know why. Again -- both Janeways were exactly the same person.
We're not talking about two different captains, we're talking about two iterations of the same captain, differing only by a few hours of experience, and we've seen
them arrive at opposite decisions. The story explicitly showed us Janeway seeing both points of view. The other Janeway was almost literally "part of" her, in that both Janeways had split off from the same individual, like a cell undergoing mitosis. So what she's saying here is a literal restatement of what's already happened in the episode. It couldn't get more transparent.