Right, but a person has to call the police and report it first, right?
I'm sure most drunken fist fights do not get reported. But in this case, getting punched in the face is at the heart of CR's alibi and defense. As the last person to be seen with LS, his account of the night is pretty important, but he can't tell the police, or anyone else because he was punched in the face so hard that he lost his memory for the entire evening after the punch (including the 15 minutes beforehand, when coincidentally, he is seen by witnesses acting aggressively toward the victim and caught on video 'helping' her walk, because she is too intoxicated to walk on her own, and presumably the point that he is confronted by a group of guys about this, and allegedly tells them off)
Yet, CR didn't call the police that night, or the next day. Or ever. When he ran into several people the day(s) after Lauren went missing he and MB told several people that LS had been at his apartment, and had disappeared after leaving. He did tell people he drank too much and went to bed, but none of these people report that he told them about being punched or having amnesia. In the only two accounts of witnesses who talked to CR on June 3rd, both report that he showed no signs of being in a fight. (Chris Malone article and anon at CVS).
The punch became a lot more important when he was named as a POI and got a lawyer.
Anyone who has been drinking is rarely going to call the police and report anything because they realize they could end up in their own trouble. The police are just as likely to ticket/arrest both and let the judge sort it out. Let alone nail both with PI's. So, no, I don't think anything is odd about CR not making a big deal about the punch at the time.
Still, the police learned of the altercation and allegedly have evidence of it (video and statements). That's all they need to take the case to the prosecutor. Or for the prosecutor to say "Let's go fishing, charge the kid that punched CR and let's get them on record". They didn't need it to be reported at the time.
At this point I'm thinking that LE must figure they have all the info about that incident to the point there's nothing to leverage out of the situation as it stands.