The woman is not wearing her mask over her own mouth or nose while she is screaming (thus projecting spit) at this AA employee who does not make the rules. Masks are required in NC and thus she is breaking the law. I truly sympathize with parents that end up in this situation but I lost my sympathy for her in particular when she endangered this employee. I get that she was clearly so upset that she probably wasn't thinking clearly but if you're going to fly during this pandemic then you need to be constantly mindful of what you are doing when it comes to safety of yourself and others.
That poor kid hasn't adjusted to wearing a mask and can't understand the situation and I feel terrible for him. It is easy to feel like the flight attendants should have let this slide but I think the flight attendants ultimately did what they needed to in enforcing these safety rules as they are written. If they did not and other passengers complained to AA then the flight attendants could be reprimanded for choosing to not enforce health safety rules. If there was later found to be a COVID cluster from this flight and it was discovered that AA employees knowingly allowed the health safety rules to be broken - I imagine that would be a problem for AA.