True, but he didn't just trust anyone off the street.  They were undercover FBI agents posing as IS which he clearly identified and pledge allegiance with.  Surely the FBI undercover agents are trained to appear legitimate so even a IS believer can be fooled.  Happens all the time in stings involving Drugs and Weapon sales, Organized Crime, and even the recent Asian U.S. Navy Officer caught giving out Top Secret Info to an Asian undercover female FBI agent.   Not trying pre-judge this young man, but in my opinion, he's indoctrinated with the radical terrorist religion of IS and it's not the first time they were found in the military.  The shooter from Ft Hood (Army Officer) comes to mind.  They observed him for at least a year, so any mental issues would be noted.  He'll be given his chance to prove if he's "mentally unfit" to stand trial.