I guess you could figure out valid states for your page's DOM, and a few seconds...

		netsharc 10 months ago \| parent \| context \| favorite \| on: Et Tu, Grammarly? I guess you could figure out valid states for your page's DOM, and a few seconds after the page has finished loading, scan it for "hostile" elements and CSS styles, and delete them... Having this idea and opening a random page (from The Guardian) on DevTools, somehow somebody's inserted scripts and iframes pointing to twitter.com.

But wouldn't you brake their extensions if the user wanted them to work?