I think that there are many good reasons for keeping sharps under control. Even today I value the lesson I learned at camp about knives. The policy then was if it was unsheathed you were using it and when you were done using it you sheathed it. This was taught to prevent loss, damage to the tool, and of-course as a safety issue. The responsible individual may be able to put down an unsheathed object while attending to some minor thing such as laying down your ax to reposition the wood. But even that individual will be less likely to lose their ax if tthey have the habit of sheathing it on thier belt instead of putting it down. (this is pertinent to camp hatchets, fixed blade knives and folders - lumbering axes and battle axes are somewhat differrent due to size.) I have never lost a knife in the woods because of this learned habit - I did have one confiscated by the counselor before I learned.

There were other rules as well:

Pass folders folded.

Pass sheath knives sheathed.

Pass fixed blades handle first with spine toward your palm.

Do not relinquish hold on blade until reciever has said "Thank You".

Sharpen your sharps at the end of any day they see use.

Clean your stones after every use

Oil your blade after sharpening

Violation of anyone of these rules was grounds for confiscation and if you were involved in an activity requiring the blade you would have to sit out till next day.

If you are going to use a tool you must care for the tool! Remember, these rules are not just to keep others safe. They are to ensure that your tools survive and that you survive. If you don't care for your knife then when you need it you will have a flat peice of steel but not a knife. If you get into the habit of putting your knife down you will one day walk away from it and never see it again. This habit is safer than using a lanyard since the unsheathed blade that follows you because it is attached is likely to jab you in the thigh.

If you present these items as proper knive care rules and preesent the confiscation as a learning / training tool most of the scouts will understand the policy. Violations of the policy need to be enforced evenhandedly and without malice. If a scout puts the blade down, simply pick it up and let them know that in a survival situation they just lost the knife - tell a story about it rolling away off a cliff because it was set down accidently instead of being sheathed / folded and pocketed. So for the rest of the exercise / day / trip they will have to survive without a blade. It is all about playing out the natural consequences.