Let's not jump to conclusions. The security officer on the ground doesn't get to make the rules - their employer or "the client" does. Sometimes those rules are stupid and senseless. You still have to follow the rules and adhere to your employer's policies.
If you're a security officer and you don't like the policies your employer has in place, your only real option is to find employment elsewhere. But with unemployment where it is currently, and where it's liable to stay for a long time to come, that leaves officers in a sticky situation where they have to ask themselves just where they're willing to draw the line. Any half-decent officer will of course up and quit in the face of illegal or amoral behavior, and future employers will typically look on that favorably as a mark of character.
But in this case, the mall didn't really do anything amoral or illegal - just stupid (and yet entirely within their rights.) The mall also didn't ask the officers to do anything amoral or illegal - it simply required them to enforce the mall's publicly posted rules by asking the patrons to leave. When the patrons failed to do so, they legally became trespassers and the police were called.
By all accounts, the security officers involved in this incident did nothing wrong. They didn't behave inappropriately, they didn't break any rules, and they didn't do anything illegal. We're not even told they were rude or unpleasant. I find it hard to fault them over their employers without actual evidence of some sort of wrongdoing.