I have always condemned violence of all sorts. This is why I think that violence is never an option. There is absolutely no reason for an employee to retaliate if he has been fired. If you think that you have been fired unjustly, then you can always take the help of law rather than taking the law in your own hands.
This is the reason why I don't support violence too. If things get to the point where it's no longer working well for you and if the company no longer want your services, there's no need to start being violent about it. You can always be employed by another company that wants your services.