I'm really beginning to think we'll never know the whole story. There has to be some culpability on Alaska's part, as the pax is claiming on social media that AS has apologized to him. If it were a cut and dry case of seat poaching, I think they'd present those facts, but they're not and they've already confirmed the dupe seating error in their previous statement.
Here's the pax's statement which can be viewed on his public Facebook post.:
"Thank you to everyone for all the support.
Alaska Airlines has reached out, apologized, and we are discussing making things right. I accept Alaska’s apology and appreciate it addressing the situation."