heavy rain combined with the freeze/thaw mention in the article is a major cause of rockfall
in squamish in the offseason, you really have to watch out for rockfall after the rain and the thawing cycle loosens out the rocks
anytime you are "hiking" or climbing near potential rock fall .... get through as fast as you can ...
if rockfall is a serious issue, wear a helmet, you can get UL ones ... it may not have helped in this case, but rocks hitting the head is a serious issue in climbing/scrambling
also if in a group, spread yourselves out ... dont bunch up in the face of objective hazards ... that way if something does happen, you minimize the casualties and have people that can respond
the squamish chief backside trail is likely one of the most popular in canada ... even it can see rockfall as happened last year