No, it's an urban myth. "To protect and serve" is only the Los Angeles Police Department's motto, which given its proximity to Hollywood explains why you see that as the motto in so many movies and TV shows. Each city has its own motto. Just as an example, San Francisco's motto is "Oro en paz, fierro en guerra" (Gold in peace, iron in war). Just a bit of trivia for you.
That being said, while there's a lot of explanations for why this cop didn't help (mob mentality, genuine fear for his life, bystander effect), it's still disgusting that he didn't at least call for backup.
My favorite thing about the word "terrific" is from the mind of Terry Pratchet
Elves are wonderful. They provoke wonder.
Elves are marvelous. They cause marvels.
Elves are fantastic. They create fantasies.
Elves are glamorous. They project glamour.
Elves are enchanting. They weave enchantment.
Elves are terrific. They beget terror.
The thing about words is that meanings can twist just like a snake, and if you want to find snakes, look behind words that have changed their meaning.
No one ever said elves are nice.
Elves are bad.
— Terry Pratchett, Lords and Ladies
"This blunt approach is not the product of an informed, open, or deliberative process"
Well, of course it isn't informed: we don't know EVERYTHING about how they're spying on us yet, so until we know everything about it, we can't make an informed decision. Of course, all of those methods are classified, so we can't tell you about them, but just as soon as you know all about those methods, we can talk about them. It all makes PERFECT sense.
Of course he was aiding the enemy. As if there could be any doubt. Any information that informs the American public of the secret crimes committed in their names is aiding the true enemy of the American government: the people it rules over.