For the first part, in theory, it's just their job. I'll never get mad at a frontline worker for simply doing what their manager has told them to do, unless it's flagrantly offensive (think racism) or aggressive/arbitrary on their part. Personally I don't ever want to be denied boarding, so I don't do anything that could risk that, but if an airport employee raises their voice at someone, they shouldn't be surprised if someone raises their voice in return. And to be clear, no AC employees I've encountered lately fit those criteria.

For the second part... can't say I'm surprised, but it is ridiculous.