Legal is where it is outlined in the law. Moral is where an individual executed action based on his personal values.
I am NOT defending the guard, I am all for him getting his wrist slapped as an incentive for him to learn the law... however you or I feel, in the guard's eyes and or whatever reason besides that, he had a moral obligation to get rid of the pictures and he exercised it, much to his possible detriment.
Again, morally he felt he had all the rights he needed to do what he did. If a police officer doesn't know the law... he'd better learn fast... or find another avenue of employment.
I agree that this was the case, but the officer was on duty is foremost a government official, he/she has an obligation to protect the rights of people and uphold the law regardless of their personal views.
The other question is did he "take" your camera, as in just ripped it from yours hands, Or did he say, "hey give me that." I you hand him the camera? you just gave him consent to take it. Did he say, "delete you pictures or I'll arrest you? Or I'll Shoot you?, probably not. Police officers are very good at convincing people to give consent, thats just part of their job. You as the photographer, need to remember to stand up for your rights,
Cop:
"hey give me your camera!"
you:
"No."
Cop:
"you need to delete those photos."
You:
"No, I do not, we both Know our rights under the first amendment. Have a nice day."
That should be the end of it. Some times, especially for young people, it is hard to stand up to authority figures, but I you are knowledgeable, and know your rights there should be no problem.
Now if you went through this conversation, and the officer, still attempted to make physical contact with you, then He has committed assault, If he did touch you, he has committed battery, if he did take your camera, he has committed theft.
This however would be extreme, most police know their legal boundaries quite well, and the above conversation should suffice.
and always be polite and respectful, just as you would be with anyone.