I would like to address some of silliest idiocy Google has trotted out in years, which is classifying the instant preview feature as a "snippet".
The only way to stop the instant preview is to install "nosnippet" in the page, at which time you also lose the ability to have snippets below your titles in the SERPs.
Technically, instant preview is a visually cached copy and any site set to NOARCHIVE is currently being violated because it's making and displaying archives of the site. The same reasons you don't want people looking at your cache, such as correcting pricing mistakes, taking down content that violated copyright, whatever, the reason you don't want cache and snoops evaluating it still apply with instant preview.
Eliminating all snippets is idiotic just to eliminate instant preview.
Can't we get a new directive NOPREVIEW, come on Google, common sense time, instant preview and snippets are MUTUALLY EXCLUSIVE.
I weep for the future.