Of course yellow is the colour of fear in the Green Lantern mythology. I mean look at it's real world applications; it's on caution signs the world over and it's the colour of Big Bird. The only known survivor of his species, one that towers over small children with a smile and a large beak, reciting A-B-C's while rumours abound there is a grown man in his belly. I mean what's not to be afraid of?
Luckily in the upcoming Green Lantern movie Hal Jordan steps up to fight yellow's influence, but from the looks of this trailer they could be saving the Big Bird showdown until the sequel.