Just because someone is younger than you are doesn't mean they might not know more about a certain aspect of your job or field. If someone has been working for a specific company longer, they have more experience than you by default with the specific demands of the job, and their age shouldn't be a factor in how you treat them. Still, it's also natural to want to protect or mentor younger co-workers and pay it forward to people who helped you along the way. Unfortunately in some office settings, there is a fine line between amplifying the voices and ideas of younger colleagues and being downright disrespectful and condescending about their youth or naivety.
So, when a frustrated employee at a law firm decided to consult the internet's moral compass of Reddit's "Am I the As*hole?" about her co-worker's offensive comments, people were eager to deem a verdict.