Some interesting discussion in here. I appreciate everyone's viewpoint.
I would agree with those of you who said to choose your battles wisely. I think standing up for my rights in this situation though, where it was unlikely that I would benefit at all from doing so, let alone promote the good of photography, was the wrong decision for me personally.I do however, think they might have still came after me simply for taking the photo under their threats and insults. But i'll never obviously know.
In terms of taking the photo in the first place, it seemed harmless to me to shoot a vehicle's tires. Of course, from the perspective of inside the hummer, it certainly could look like I'm shooting them. I didn't think that far in advance given it was late and i had a few to drink. lesson learned there.
The beauty of people to me lies in part to our diversity. While some hold their principles so high that they would risk their safety to defend it at any costs, I think it would be arrogant for me to tell that person what the "right thing" is to fight for, and what isn't worth it. It is a value judgment, and everyone's differs and we are free to disagree, but maybe not judge. I can provide my opinion from my perspective, my life experiences etc..
Hindsight is certainly 20/20, and I will be more cautious in the future but not afraid. I acknowledge the comment about putting my friends safety in jeopardy, and thought about it. Three of my friends i've known most my life, and they would fight to the death protecting me or eachother. I do not like to place them in danger on my own account, so I think my biggest regret was with their safety, not my own.
I am happy to see some discussion. Cheers