Knock it off.
It’s no picnic writing software updaters for an ever sprawling empire of code. Sure. Mistakes are made. Granted. But hijacking an automatic update to install a plugin I never asked for, don’t want, and have no way of opting out of (and throwing me off my browser session to boot)? That’s software update rape.
Until I tell you otherwise, what happens in my browser is my business, not yours. Get thy plugin from out my browser, and take thy form from off my desktop.
If you’ve updated Acrobat and find your copy of Safari likewise commandeered, you can slap a muzzle on the interloper by chasing down the following maze: Acrobat menu > Preferences… > Internet > Web Browser Options.
Uncheck “Display PDF in browser using”. (Oh, and while we’re at it Adobe, don’t use a dropdown box when you’re only giving the user one option.)
For good measure, uncheck “Check browser settings when starting Acrobat” to keep it from nagging you to turn the plugin back on again (until Adobe sneaks in and does it themselves during the next software update, that is.)
This will get you back using the much, much faster Preview app for viewing PDFs in Safari. Unfortunately it doesn’t mean it’s going to stay that way the next time an Adobe updater comes bouncing your way. For shame.