The biggest thing being overlooked here is the context of the play. Yes, lag spikes are part of the game. If it were a season game, I would agree, you should bite the bullet and take the spiked goal and move on.
However, this was a tied critical game in the finals with a few minutes left in the third... and it was between two veterans who aren't named wags or dcicon. I think most people would expect a vet (thus making it an unwritten rule) to give back the spiked goal and try to win in a legitimate fashion, rather than take the win on a quasi-legitmate goal.
... And I think that's the biggest problem: Even if there was a good chance that seth wouldn't have prevented the goal, why take what would probably end up as the series-clinching goal off of a quasi-legitimate play?