Maybe the judge was talking to the Kalpoe brothers lawyer and what he said pertained to them and not Sloot. Near as we can figure based on the stories coming out, the brothers lied to cover for Sloot. Lying is not a crime and they may not know why they needed to lie. But, Sloot on the other hand, has also changed his story and his explanation won't be so easy to explain.
Doesn't mean he murdered her, but it could mean that he is trying to avoid being charged with some crime. I'm guessing rape.
I suspect Joran raped Natalee and then, when she screamed, covered her mouth and nose, trying to shut her up. He realized he'd killed her, and perhaps the Kalpoe bros. were there, watching. But they know what Joran did, and their skedaddling back home says they wanted no part of a murder charge. They were scared to death, but maybe they helped Joran get rid of the body, then they came up with the first cover lie, split up and Joran walked home. When J got home, he immediately let them know he'd arrived safely. This behavior makes no sense unless they were all involved in something terrible.