Maybe he was just trying to get the story out there that he was "put to bed" and didn't remember anything in response to (or in anticipation of) people looking for Lauren. They seem to have mentioned this to a few different neighbors early on.
It's true that it's hard to read these comments without more context. But I think the reactions of other people are telling. It doesn't sound like they came across as totally normal or convincing to those around them either.
If you heard that friends or neighbors were the last people seen with a missing girl, wouldn't you probably believe and defend them if they said they had nothing to do with it? This didn't seem to be the overwhelming reaction to the guys at 5 N in the days following Lauren's disappearance. Their stories were publicly questioned by people who knew them on FB and there were reports about an angry confrontation at 5 N. And at this point, the only thing people had to go on was rumors.
The witness statements also seem a little skeptical. The guy who told the story about CR looking for a little blonde girl, adds:
The friend who ran into them at CVS, tells the story that MB told him, and as context, describes CR and MB's relationship as:
On PT, the reaction to JR was similar. "Ray" described the odd and uncaring way that JR told his roommates about the situation, telling them that police had come to the apartment and stressing that "it wasn't his fault". He also described JR as a liar with "no soul". To be fair, I believe he said he didn't think JR could be responsible for Lauren's disappearance, and there were others who agreed, but even then, the main objection, IIRC, wasn't that JR was incapable of a heinous crime, but that he was "too stupid."
I think the only person who really defended the POI was HT, when she told JR's story to the media and said she believed him. And all that did was convince most people that HT was lying or in on the coverup...
All this to say that I don't think we're reading too much into it and that these stories sounded totally legit at the time. They always sounded awkward and strange, IMO.