Interesting that the company gave no warning or cease and desist. Maybe their policy is well written out and clear? The company I used to work for had my signature in blood on a paper saying I would not speak ill of the company publicly nor do anything in my private or personal life to harm the company.

I was warned on two different occasions about behaviors they disagreed with. One was posting a message forum about the company as an identified employee and getting into a pissing match on there with a customer. The second was an inter-company debacle where I openly questioned the quality level of work produced and customer-unfriendly practices by a different segment.

Both garned a "do not speak ill of the company" stern warning from my supervisor, a new paper i had to sign reminding me that i had signed the first one, and a not on my record. I was stil promoted and offered other positions before I left the company later on - but they certainly made their position quite clear without canning me outright.