You don't get assimilated.. that's the reward for not colliding with the enemies. So letting them past is fine. Manny lived. You just don't get points for that.
About looping the music, I wanted to do that but was unable to do that for the mp3 audio clip. Some write ups claim that it can be done but that option was not showing when I traversed the options available.
Thank you for the feedback. Will try to ask around on the audio looping.