It was reported before that he had the FBI and a few other organizations work for him. I'm sure they've given him a good idea of what to cover and what not. I think he's doing a great job - very forthright.
If we're comparing to Kyron's case, they've been so tight-lipped, I think it's hindered their investigation. Important information about Kyron's appearance wasn't coming out until a month after his disappearance.
I don't think anything that's been revealed could compromise the investigation, and I do think there's something to be said for laying out the facts as they stand. He's been good at stating he can't reveal certain information because of the ongoing investigation - I think he's doing a good job sharing some info, because otherwise, I could see there being a lot of panic.
I don't know if we can use the sharing/not sharing at pressers as an indication on whether the investigation is going well or not.