ok I understand the no campfires buy why the no alcohol - is there some assumption that as soon as it touches your lips all hell will break loose?
It's in case the lawful orienteers get into a brawl with the disorderly trailbikers boozing it up unlawfully in the same area. This way the authorities get to regulate at least one group.
I assume it's a blanket National Parks rule - they're probably sick of picking up broken beer bottles (which will probably be analysed as "middens" by the archaeologists of 2500...).