It's neither laying the groundwork for future presidents nor members of Hell's Angels but I see no reason not to at least make a respectable, honest effort. And I certainly see no reason to do it in a way that is just sloppy and somewhat disrespectful to the process. Most Boy Scouts were Cub Scouts first, so I'm sure this prospective bugler would be more than familiar with the Cub Scout motto, "Do Your Best". It's an ethic that's part of the Scout culture.
Regarding learning the bugle, itself, if it were me, I would write out exercises that gradually work themselves up to G3. Using just the bugle calls are IMO too much too soon.
To give you some ideas, or to get you started altogether, there's a US Navy Manual for Buglers that has some reasonable exercises that are gradual. Go to Manual For Buglers, US Navy and check it out. Don't be fooled by much of the text in the beginning. Scroll down to almost the middle to Chapter 5 and there are lessons there that you might be able to incorporate into your teaching.
I would probably use as many as practical but not going beyond the eleventh week lessons, and add to them some that I would write that had some rhythmic bounce to them. Maybe even getting around to using the rhythms of the bugle calls the scout will need to use on his required calls but is not yet able to play because he doesn't yet have the range under control.
Good luck. Have fun. Remember - be firm, be fair, have fun.