It appears that the gate agent who denied Mr. Alvarez a First Class upgrade believed Alvarez was a non-rev, was dealing with another customer during the interaction, and is a non-native English speaker.
From Robin Urbanksi, United’s spokesperson:
We are working with our sub-contractor that was helping us with this flight to investigate what happened and ensure something like this does not happen again. This was an unfortunate miscommunication with the gate agent who speaks English as a second language and was simultaneously assisting another customer when he believed Mr. Alvarez to be an airline employee in which a dress code policy is required.
One side of me wants to scold UA for making excuses, but I do commend UA for quickly getting on top of this story and confirming their policy that there is no dress code in First Class. I hope that all the news outlets that reported on the initial story will also report this.
I have a three hour connection in IAD today and will be there for about an hour tomorrow as well. I’ll be coming in on United Express tonight and plan on doing a little sleuthing. Stay tuned, maybe I’ll have some breaking news to report tomorrow on this matter!