Sanji used RS to not be recognized by Drake and Hawkins duo. If Sanji couldn’t incapacitate P1 fast enough, Drake and Hawkins would come and directly recognize Sanji from his face. With RS, even though Drake and Hawkins would catch up, they would not be able to recognize who Sanji was and the plan would not be put under danger.
Sanji’s plan was logical, however, he did not take bath house incident and Drake/Hawkins duo being from North Blue into consideration, which enabled Drake to recognize Stealth Black was the same person with Sanji. (Drake is a Marine spy so he probably has access to all of the news from the world.)