I'm not sure about any major conspiracy, but I will say this...
I think it is ENTIRELY possible (and probable) that officials are influenced by subtleties that even they may not be conscious of. Home teams, particularly ones with strong local support like the Saints (and Seahawks) seem to get more favorable calls, NOT because of a conspiracy or deliberate attempt to placate fans, but more out of giving them the benefit of the doubt. It's easier for officials to call a ticky-tack play on a visiting team than on a home team, particularly at a critical point of the game. If the Falcon game were played in Atlanta, I am certain that Sherman would have been flagged for PI. This game was in New Orleans, a city the NFL has been in LOVE with since the Katrina disaster. The Saints are going to get the benefit of the doubt in such circumstances.
Even seemingly minor factors, like the "Everyone loves Brees" factor, can quietly influence officials. I firmly believe that Peyton Manning benefited tremendously from that factor, and I also believe that one of the reasons for the decline in NFL viewership is because Manning is out of the league. The NFL is trying to find his replacement, and Brees is one of those top tier QB's that draws in the same type of fan that liked Manning. Just my observation, but I have noticed many acquaintances and friends that LOOOOVED Manning now no longer paying attention to the NFL as much (like my mother in Law - huge Cowboys fan but bought all kinds of Peyton merchandise).
The NFL is a business, and it benefits financially if certain teams and their markets are competitive. Seattle could afford to lose on Sunday and still be in the playoff hunt. It was MORE important for New Orleans to win to stay competitive, and that is where the hidden and subconscious favoritism may play a role.
Remember Super Bowl XL? The Bettis homecoming? I was convinced then, just as I am today, that Bill Leavy and his crew were going to give Pittsburgh every benefit of the doubt, whether they were conscious of it or not. The world was not ready for the Seahawks to win the Super Bowl, and the media and global fan base wanted SO BADLY to anoint the Steelers as champions and have Bettis go out the way he did.