Reading through the rules for Surprise Attack and Hidden Deployment, it seems a Nadhir can't use Surprise Attack. Hidden Deployment isn't listed as a Marker state and doesn't have any text allowing Surprise Attack to be used the way Holoecho and Impersonation does. Am I missing an important piece of text or is Surprise Attack on Nadhir not supposed to be on the profile?
Either that, or the rules for Surprise Attack are supposed to say that you can use it by attacking from marker state or from hidden deployment. That's my guess, but either one is possible. If they finish up all the Army bug fixes and Nadhir still has Surprise Attack, that'll be pretty strong evidence that it can be used from hidden deployment. Incidentally, RAW a Swiss Guard (or any "TO Camo" troop) can't use Surprise Attack from hidden deployment either. They have to spend one order Moving to go from hidden deployment to marker state, then another order to Surprise Attack. Which would be weird, like it's less surprising for someone to appear out of nowhere and shoot you vs. appearing from an area where you suspected someone might be hiding. Which doesn't make it impossible, just unlikely that CB intended it that way.
Missing text from the Spanish rule is already flagged for an FAQ. Surprise Attack works from Hidden Deployment.