I believe if they found anything illegal he would be held or atleast charged with something.
Feds aren't on anyone's timetable. They bring charges once their case is ironclad. If that takes months, a year, or a few years that's what was needed. He definitely should not feel like he's in the clear. The raid on his home may not have been the primary target. They could have evidence from before that or they're still getting it elsewhere.