Probably the biggest reason is they figure there is a better chance of selling tickets for this game @ Giants Stadium. The Saints could well end up playing all of their "home" games at the opposing team's stadium.
Based on what I hear, they will be lucky to ever play in the Superdome again......
Mep. This might prove to be a morale buster to the Saints...then again, the NO tragedy might be a big motivator. Who knows?