Unlike in the movies, Bastien was not knocked out after being hit by Peter. Instead, the man fell to a knee and dropped Olivia in the process. He held the back of his head cursing in pain. He was clearly caught off guard by the assault, and it took him a minute to come to his senses; a delay that his attacker exploited.
Peter could hold his own in a fight, but he saw no need to use his fists when he still held a heavy object in his hand. He used it to keep hitting Bastien before the man could react, and he finally got the result he was looking for.
With Bastien dazed on the ground, Peter bent to check on Olivia, whose face was still grave. He knew it was because of the past invitation he had given her. To Olivia, it did not matter if he had just saved her from someone. She was still a woman, unable to do anything to protect herself, and he was a man who she knew wanted to sleep with her.