The USAirways.com seat map is not an accurate indication of the inventory. Just because there are, say, 4 open seats doesn't mean there's 4 UNSOLD seats. When I book corporate travel I usually don't bother with making a seat selection; I genuinely don't care, and I don't bother going back and choosing a seat till I OLCI. Codeshares also sometimes do not allow a passenger to select a seat. So don't assume that just because the seat map said there were X seats empty, means that there are that many seats unsold.
The "extra year" of Gold is someone who doesn't understand the subtleties of the program. When you qualify for Gold in late 2010 it is good thru Feb 2012, and when you qualify in late 2009 it is good thru feb 2011. So this other gold is not in an "extra year" of Gold at all; he's still on the benefits of what he earned in 2009. I'm not sure who outranks who when it comes to day of travel upgrades--- I do know that BIS miles come into play at some point--- but it does sound like this fellow did the chivalrous thing and let his wife ride up front, or that they paid in miles or even a "go" upgrade.
and when someone says they haven't flown that much this year, it's all relative. If I dropped down to, say, a quarterly trip to England and nothing else, I'd consider it not travelling at all but I'd still be getting over 20k BIS miles!
At any rate I don't think we will ever get an answer from US as to why one passenger was chosen for an upgrade over another passenger, but it's good to keep in mind that the seat map doesn't reflect reality, just so we don't torture ourselves on the details.