What don't you understand about this?

From doc 911: In the same vein, if the landowner for your club’s chartered club field has granted the club exclusive flying privileges, the club should ONLY allow AMA members and current members of the Model Aeronautics Association of Canada (MAAC) to fly at the field. If your club is flying on public land and it has not been granted exclusive flying rights by the public agency in charge, your club activities should be confined to AMA members, and you are not responsible for other (non-AMA) flier’s actions. Should the public agency be named as an additional insured, it has coverage only for the actions of your club, its members, and other visiting AMA members who are considered guests.

You do know what "should" means don't you? I mean how can you be not responsible for other (non-AMA) fliers actions if they do not allow dual charters at flying sites??? If you read the entire document from start to finish you'll understand why it does say "should" and does not say "must", multiple times. They give you a nice sales pitch in the entire 911 document and they should, that's sales 101. I agree that it may be a bit confusing, but it's in the best interest of the AMA to preserve and grow the AMA, that's their job and mission. Kudos to them for making you think this way. The AMA does not control us or our flying sites, they are only providers of suggested guidelines, insurance and a really cool magazine, along with other perks that some use and some don't. The AMA does have it's limit on how we live and breathe.