The primary issue I see when a passenger raises the issue that their seat is being encroached on is to reseat the passenger who has raised the issue, and often they are reseating the passenger to a worse seat. While it's nice that the FA in this case offered to reseat the OP, I don't think it's appopriate to move them from an E+ seat which they have paid for either through status or in cash. I've only seen one situation which I though was handled well. There was a very large passenger who really needed two seats, and they upgraded the person sitting next to him. It was done carefully, and the passenger who was encroaching on the others person seat didn't seem to be aware that the other passenger was being reseated due to his size.

I feel for the FAs it's a very difficult situation, i think the airlines need to come up with another procedure for resolving these sorts of issues before its left in the FAs laps.