Either the guy is/was delusional and his 15 min of fame (like mentioned below) blew up in his face, or the systems are vulnerable and it's being downplayed (while hopefully it's being fixed).
At this point though, it's difficult to trust FBI and a corporation that has a lot to loose...
I think Boeing needs to bring in independent researchers and let them loose on some planes on the ground, either proving or disproving this whole debacle...