TBH, from a rider’s point of view, you’d never want to be in the position of worrying about hitting spectators. However, my experience from very low-key DH events is that having ‘rules’ is one thing, but getting people – spectators, or fellow competitors – to understand the reason for them, let alone to stick to them, is going to be tough.
As a marshall, getting people to stay off the track is a total pain in the arse. “But I want a picture of my mate” “But I’m not in the way”, “But I’ve got rights” and really no practical recourse if anyone decides not to listen to you. Not suggesting anything of the sort happened here, but it’s an issue for crowd control in general. I clipped a photographer in an XC race once, he said “You were going too fast!”