RRDD, that article was unintentionally hilarious. cohen "always paid for a full-fare first-class seat" and is complaining about seat-swap requests from people who "are often upgrades to first class traveling on cheaper coach fares." sorry to break it to you, mr. firster-than-first class, but there's only one first class.

this topic comes up pretty often. there is no special rule: everyone is entitled to ask to change seats, but no one is entitled to insist on one. and separated couples should remember that they have two choices for which seat to offer in trade, and offering the better one is more likely to be well-received than offering the worse (e.g., when i was upgraded and separated from my spouse, i happily gave up my F seat to be next to my spouse in coach).