While a GPO exists to block WU from auto-installing Previews, no policy exists to hide them from view.
Someone will chime in to suggest running WUMT or some WU blocker. Those don't really help, you can hide a specific KB only after it's offered. What they can't do is automatically hide a KB before it appears.
Unless you want to play "whack a mole" and hide each month's Preview as they show up.
Seeing "You're up to date" is a good indication that any update listed is optional. That should be a good flag for the user to examine anything that follows before choosing to download it.