Almost assuredly yes, though the Black Panther Party would be a better example.
>Are the looters in the Ferguson riots "terrorists"?
Yes.
>Are the countless people who are in prison all "terrorists"?
Many, yes. Prison can be very radicalizing, especially since gangs form along ethnic lines, which suggest political outlooks.
> Just because something is criminal and political doesn't make it "terrorism," as much as law enforcement and prosecutors would like you to believe otherwise.
I don't see how you can make this assertion. Breaking the law means you are rejecting the fundamental foundation upon which society is based. If you reject that, you are open to all possible outcomes. Any act of breaking the law is a rejection of all law and with it all order, stability, and moral uprightness.
Are you not afraid of that outcome? Does it not strike fear into your heart? Or did you watch The Purge and think it was some sort of comedy?
Martin Luther King Jr.'s tactics were appropriate for his time, but today we live in a different time, and they would be considered terrorism. Anti-war protesters are frequently terroristic. The Occupy movement was overtly terrorist, as it intended to cause economic harm for political ends.
It's important to always remember that while people might advocate for causes we agree to in principle, we live in a society of laws and rules, and we all must stay within those rules. There is a beautifully documented, perfectly effective mechanism in our society for effecting change: liberal democracy. If the change you wish to make is true, right, and just, it will inevitably take place without any requirement for lawbreaking. All you need to do is call your representative, and vote. Problem solved.
However, if you go outside of this, you are a terrorist and you deserve to be targeted, hunted, and eliminated by the state, in order that our society be protected, and that we all be able to continue to live in prosperity and peace.