Not sure why you would consider telling the older scout the expectations for participants would be considered rebuffing him. It's being honest, and letting him make a decision as to what is important to him. As much as we would like, we cannot have it all.
Some units choose to start the crew bonding with the crew training. There are advantages to it. Other units need not make the same choices, I agree that no trek will be perfect, but you can help the crew put the odds in the favor of having a great trek by preparing together, That benefit is HUGE.