Yes, it was.
> But that's the point of protest!!
No, it is not.
From Cambridge Dictionary: "protest": a strong complaint expressing disagreement, disapproval, or opposition.
You can express your dissenting opinions without being rude. And, by the way, the monarchy has been in UK for centuries, and it is still there: if you don't like it, you have any day available to protest. No need to pick that particular day when you can be most disruptive.