You mean how Delta doesn’t call it “her seat” but rather “the seat she reserved and paid for”? There’s a reason for the careful language – it wasn’t “her” seat. “Her” seat is the one on the ticket. Delta is apologizing that the one on the ticket didn’t match the one on the website but “…the seats noted on their respective tickets…” are what is actually “your” seat. Which is why that’s where she wound up sitting. As previously noted a couple times in the threads, your previous seat reservation is not binding (even if Delta says so sorry after you throw a Twitter Tantrum). What matters is your ticket.
I so wish that Delta Force was part of this story.