Well you should, in fact if this bothers you now, why haven't you spoken against them before?
You aren't being selective in your outrage, I hope.
People are free to express themselves however they wish. I neither support nor condemn it, but approve and accept of their right to do so. When it comes to something,ike flag burning, you're either supportive of the action or you're against the action if it disrespects the causes you adhere to, which would make you a hypocrite. People can burn the Union Jack for all I care, it means nothing to me as I don't care for it nor would act in such a way. That's their opinion and it's one I don't share, but I respect their right to do it, same with burning the EU flag.
Nothing more.