I trust most FBI agents in most situations. As for the ones at an ambush after a promise of safe passage, I find trust difficult. I imagine LaVoy felt the same. He may have believed (perhaps correctly) that, armed or not, they would find his gun in his pocket/holster/waistband after shooting him. He may even have followed your advice, and they still found guns on him.
It is not clear to me from the video whether LaVoy was reaching for a gun/pocket, steadying himself on uneven snow, or actually shot before the movement that is claimed to have provoked the shooting and reaching for where he was hit. What is clear is that they were prepared to kill at least one of the people promised "safe passage", to make sure that decent people get the message - Obama's minions will not tolerate anything less than worshipful obedience.
Regardless of the circumstances, it’s hard to have any sympathy for someone who is gunned down by a law enforcement officer after spending months broadcasting all over the media that he’s never going to be captured alive.
Would not be difficult to have a silenced .22 rifle put a round into his side, just so he would reach for it.