He obviously locked his knees. He got right back up. What a stupid thread. 
Like your assessment... by looking at what others said in the comment section

How is it OBVIOUS?

The guy could have passed out from a number of reasons, none of what were known or could be assumed at that time. Maybe locking his knees could have been a cause, but is that reason to drag him over to a back wall like a sack of dog shit or something? And noticed no one else even reacted as though the RITUAL was so important that all else failed to become relevant. Good hing the guy was not shot by someone with a silencer...by the time those idiots would have gathered enough thought to say something is wrong or we are being attacked the bulk of them would have been dead.