The surprise for a human player won't gain the deepmind AI much advantage. A human can recognize the concept "I am being worker rushed" and immediately counter it, necessarily having more workers at their starting site than the attacking player who sent only their starting workers.

As the grandparent stated, a worker rush only works against the built in starcraft computer player, because the computer AI is too dumb to recognize "I am being worker rushed" and may not commit all of its workers to defending.