It’s been over a week since the kid was outed on the web. Plenty of time to wipe his hard drive and clean the house of any incriminating evidence.
The FBI has the log files from Yahoo and the hacker's ISP. The operator of the proxy server has turned over his log files and is cooperating.
There is no point in getting in an uproar if the indictment isn't handed up today. If David Kernell was the hacker, he will be indicted soon and brought to justice. If his roommates took the fifth, they'll be given immunity and compelled to testify.
The more interesting question is whether the FBI can catch the other hackers who logged in after the first one disclosed the changed password.