I agree Dana, that's how you would execute the technique. It's a good technique as a double strike to the ribs and a grab, but you still have a dropping of ones guard to execute it. What this means to me is that the other person is mentally or physically out of the fight for that moment, or they are a real tomato can. It's this view that makes me think that the arm crossing move has got to have a little shock and awe stored in it to allow you to execute the next move.
A few ideas of what the crossing arms mean to me:
against a punch or single handed grab the arms crossing can be dropping the elbows onto the back of the hand, a cover against a straight punch allowing you to follow the other guy back continuing the sequence, a ready position that makes the other guy have to go around your guard giving you his center with enough shock and awe targets to get you to the next sequence.
Against a two handed grab or choke the crossing arms are dropping onto the nerves on the forearms. This moves their head right into the outward movement which could be strikes or thumbs into the eyes. That should soften them up for a split second for the rib attack and move.
These are just how I would or have used the move, others with more skill than me and actually know Uechi (unlike me) will have their own, and better, interpretations.