Meh, ignore the troll.
Just curious... what do you think the odds are that the mo-cap guy is Doomsday?
It seems a little unlikely, but well, Doomsday was created on Krypton, and the mo-cap guy is wearing something on his head that supposedly is the focal point where the other actors are supposed to look when they look at him, which indicates that the CGI creation will be much taller than the actor.
Doomsday is pretty much just a mindless brute, so he could make good "ultimate henchman" type of villain. And I know he'll forever be tied to the death of Superman, but just because he's there doesn't mean they'll go the death route.
Just some food for thought. I highly doubt that we'll see Zod or any actual actors in CGI suits (a la Green Lantern), because when Snyder was asked if Superman would wear a CGI costume, he made a remark about how that wouldn't make sense. And if he has that attitude about the Superman suit, my guess is, he'd have that opinion about other Kryptionian characters.
Thus it would appear that mo-cap man will actually be some sort of monster or other all-CGI creation.