That headline is a pretty deceitful casting of the actual situation, which is that UA can permanently ban annoying jerks who won't stop bothering everybody when asked.

Airlines can permanently ban passengers at their discretion. The specifics of behaviors they may consider disruptive aren't that important particularly when they are reasonable (not wearing headphones while listening to audio content could be considered disruptive to other passengers, after all).

... while listening to content on their flight.

The headline here is ridiculous. You dont have to wear headphones. You just cant play podcasts/music/movies/whatever on speaker.