By retiring the number 12, and lofting a banner to be displayed prominently next to the HOF'ers banners, the Seahawks probably had several meetings to discuss how and what to inscribe above that number 12 so that it simply was not left blank before they did so.
Just like they did for "Hooshyourmama", they could have used the same small letters to install "Your Name Here" above the "12", but they chose "Fan" instead. Somebody made a judgment call. Not having researched the decision on the term "Fan" before this post, I have no idea whether it was a group decision, or one made by Allen himself. Either way, it was chosen from several ideas that didn't make the cut. It was the safest choice, and there is nothing wrong with that.
All that being said, (and I've said it before) my personal preference is to wear the jersey of a given player to honor them and their contributions to the team in the course of history, and to let the world know I am a Seattle Seahawks fan. If that player left the team somehow, I feel the contributions they made while here are more than enough coolness to qualify that player's jersey to be worn proudly. Although I fully respect the positions that my friend RiverDog and others have laid down, I am among those with an opposite viewpoint on the subject. I might take a moment to consider whether that individual didn't kill anybody innocent in a drunken crash first, but that's about it. If that player did at least one cool thing on the field of play, that's all it takes.
To me, being in line at the grocery store wearing my #4 Dilfer jersey, or my #30 Ahman Green, and having a random person say, "wow dude, that's rare/random Hawk's jersey you got there man!", well... that makes my day. To wear the jersey of a player that was part of Seahawks history, however brief and/or unsuccessfully, is just my thing.
If I see somebody wearing a David Carr Texans jersey around here (and it happens...), I'm the one dude that will say something to that person. I'm like: "Hey man, did that guy ever wash all the pieces of turf and mud out of his butt-crack?". Then, after some lighthearted chuckling, I'd follow up with some empathy, like: "Seriously, if he had a decent O-line and a coordinator, he might have lasted a lot longer", which might be the olive branch statement that Carr-jersey-wearing guy needed to make wearing that jersey possible in the first place.
I mean, that DC jersey may have been the only thing clean in the pile on the floor that morning. Or dude may have picked it up at Good Will for .50 cents, but that is irrelevant. He is wearing a part of NFL history, is an NFL football fan, and is not taking the safe route. That should be an effort that is applauded, not ridiculed. Like those that wear shirts and hats for a political candidate they support, the person that dons that Kelly Stouffer jersey is letting the world know that a choice has been made, and there is absolutely nothing wrong with that.
Nope, "Fan" never played a down in a real NFL game. He did pay thousands for tickets and airfare, and was there when Ryan threw that pass to Gilliam last year and he should be respected for that. But he is not me, and that is just fine. I will high five that person anyway, because that is his/her personal choice, and we should all be glad we have those choices to make.