Eh, while it's true that he probably has a bad set, it's not like there aren't unique things happening to the cranks on a fixed gear.

A road bike crank only ever experiences tangential force in one specific direction, and this is not reversible or subject to assembly error. It's not inconceivable that a manufacturer could design cranks to be stiffer in one direction than the other, and I'd even say it would be smart.

Whether or not FSA has done that, I doubt it. But it wouldn't be illogical if they did.