Sounds like they wouldn't hesitate to apologize, if it wasn't to a manager. But it seems, in this case, it doesn't matter wether she is a manager. Not apologizing would not further class struggle nor raise class consciousness in any way. Apologizing doesn't cost anything else either. On the contrary, they want to do it. She probably needs to hear it. It's good for the emotional health of anyone involved, including the one apologizing.
I say this, not despite being a Marxist Leninist, but precisely because I'm ML: capitalist, worker, manager and (dare I say it) even cop. Those are all just roles people take on. The roles can change, but we're all still humans underneath. You can love your enemy and still fight them, when necessary. But if it doesn't serve a purpose and even makes you feel bad, why bother being mean?
The Nazi and fascist theorist Carl Schmidt (who's still very influential) viewed politics solely in terms of friend and enemy. And being an enemy to him is meant existential, personal and eternal. He wouldn't have apologized. Marxists know, that class is not about who you are as a person, but about the social role one occupies. We can distinguish between interpersonal conflicts and class struggle. The true enemy is the class relation itself.
That part was really emphasized historically, which kind of hid the underlying dialectics. If you only focus on the "synthesis" part, nature seems static. But now, new research is bringing out thermodynamics dialectical nature with the attention shifting towards non-equilibrium thermodynamics. I like, how such an old field can still change and grow. By the way, they are also shifting to new definitions of entropy as observer dependent.