Kind of funny seeing maybe some google naivete and the "do no evil" thing come back to bite google.
When I was in high school I had a fair bit of fun going outside the permitted guidelines. By college I'd developed a reasonable sense of boundaries with other folks equipment / jobs with a trust element.
If I pushed a pop-up notice out company wide with a message my employer didn't approve of, I'd definitely be expecting to be going out the door rather than doing the litigation process.
Having worked a bit in govt interesting to see the NLRB pursue this, in govt my experience was a REDICULOUSLY dim view would be taken of something like this.