Isn't it the a distinction without a difference ? Apple isn't providing your real eye movements, but an 1 to 1 reproduction of what it tracks as your eye movements.

The exploit requires analysing the avatar's eyes, but as they're not the natural movements but replicated ones, there should be a lot less noise. And of course as you need to intentionally focus on specific UI targets, these movements are even less natural and fuzzy than if you were looking at your keyboard while typing.