I suspect this snake was bigger than 3m (10 ft). One that size isn’t too much of a threat. Now, the 10m (30 ft) variety is a different story. ;-)
The only way I could see this happening with a snake that small is if he’d draped it around his neck while handling it. If it quickly constricted around his neck he might have been overcome before getting it off.
What's with the "crushing" part? I thought they just kept constricting each time the prey breathed out until it couldn't breathe anymore.