And no, of course nothing is ever simple. That's a big part of why we have courts in the first place.
But in her case, she was well known where we lived and since my business was B2B it's a far smaller community than B2C. Her bashing Planned Parenthood would have been really, really hard not to come back on the company. Again, she didn't do that, just hypothetical.
But again, while what you say is reasonable, legally it comes down to the employment manual. I can pretty well restrict my employees social media activity, but I have to be very specific. The default is there is no restriction.
Believe it or not, I had to put in things to the point of they couldn't take cash out of the register for personal use without WRITTEN permission. Otherwise they can argue it was a verbally approved loan and it can be a lot harder to prosecute them. Same with computers and other company equipment. It's something the way it works