So just because you agree with their cause that makes piracy acceptable? What delusional world are you living in? Acts of piracy/terrorism are NEVER acceptable just because you happen to agree with the cause.
Where do you draw the line between piracy/terrorism and justified violence? Is it justified if you have a majority on your side? Calling something a terrorist act is just branding it as evil. It has been said earlier that terrorist is the new communist, you can justify almost anything with it.