BCAAs are amino acids. Proteins are broken down into amino acids in the stomach and small intestines and then absorbed through the small intestines. Amino acids such as BCAAs are just absorbed through the small intestines.
Once in the bloodstream, there's no difference because they are the same thing.
There's nothing wrong with BCAAs. BCAAs are great. They are an important part of protein.
But a couple of grams BCAAs don't "give you long term energy" any more than a couple of grams of protein. That doesn't make any sense at all. Your body can and will use amino acids for ATP production in the Krebs cycle. This is why a gram of BCAAs contain as many calories as a gram of protein - they both produce the same amount of energy when used as fuel in the cell.
During exercise, your muscle cells will primarily break down stored glycogen to produce glucose and then use that glucose directly to produce ATP (energy). The longer you exercise, the more those muscle glycogen stores and blood glucose get depleted. The liver will begin to break down its stored glycogen to maintain blood glucose levels, but it will eventually run out -and in someone not trained for endurance it will have trouble keeping up anyway. This is the reason sports drinks pretty much all have simple sugars - they are designed to help boost blood glucose levels to provide the cells with the fuel they need to continue working.
This is very different from a "sugar rush" while resting. When just sitting around, blood glucose levels are normal and you don't need extra fuel. A sudden infusion of glucose raises blood sugar levels which causes an insulin spike. This is completely different than glucose supplementation during prolonged strenuous exercise. The physiological situation is completely, completely different. Ingesting glucose during prolonged exercise will not promote diabetes and any such claim is absolutely ludicrous.
There's nothing wrong with BCAAs before, during, or after workouts. Nothing at all. There's a lot of evidence to support the idea of having amino acids entering your bloodstream during exercise to maintain nitrogen balance (prevent muscle breakdown). Whether this comes in the form of BCAA pills right before/during exercise, a whey shake half an hour before exercise, or a piece of meat an hour before exercise doesn't make that much difference.
However, the main point here is that he will be performing strenuous exercise in difficult conditions for longer periods than he is trained for. His body will be facing depletion of glycogen, water, and ions. In order to maintain good functional levels, he needs to replace them. The way to do this is by ingesting water, electrolytes, and glucose. BCAAs are fine if he thinks they may help prevent muscle catabolism, but BCAAs by themselves are no better than a complete protein (which includes BCAAs) ingested an hour or so before exercise.
If you play by the rules some might consider you a *. If that's a problem then, by all means, give away as many points as necessary for their approval