As far as the guard getting his weapon taken away, considering I've seen several incidences of police getting their guns taken from suspects (granted, from their holsters more often than not), I believe it. You don't expect someone, having already been warned, no matter how stupid and arrogant, to suddenly do attempted murder directly in front of your crew. So you relax a bit...just enough for them to do something lethally stupid and catch you flat-footed.