There are a few issues with this in my mind
First of all look at the age and ability range of the riders - some young riders with no fear, a few professionals and an awful lot of over 40s who will be expecting to go to work at some point the week after. Its a single route trial, by nature some sections will be too easy for the pros and other sections too hard for the clubman.
Second, would you prefer they rode in the begins and stalled the bike, or rode to the foot of a waterfall and turned round ?
Third how do you know those who didn't get a ride would ride every section ?
Fourth If you have sections the majority don't attempt then is it the majority of riders who are wrong or the section ?
Finally having bought a new bike, new gear, paid the entry fee, drove to Fort William, paid for the hotel etc etc, why should a clubman put himself out of the trial on Monday before lunch at Blackwater or Grey Mares by hurting themselves or their bike on a section the majority are going to five anyway ?