I honestly would go trying to teach them how to use a muzzleloader,a s your new at it yourself
WHY make the work and efforts, when you could spend a fraction of the $$ on .22 ammo and let them have a LOT of shooting time in with a LOT less risks of anything going wrong!
a s i gather they will also enjoy shooting something they can see the target after the shot is fired!
from there Maybe go forward pending there plans and all
a bunch also comes down to your budget here too!
I would think most new shooters(and I taught a few hundred over the yrs)
all just want to learn basic's and nothing beats a 22 for teaching IMO
a good bench, a close target and good safety gear, good instructions and they will have a BLAST, you can stretch distance as there skills evolve
and then, maybe add different guns to the fun, like a shotgun(as again ammo is cheaper)
they can try there luck at shooting a moving target(clay bird)
and have stories to tell of there shooting when they go home!
NOW<> there is NOTHING wrong with a 50 caliber flintlock for bears, as long as you use the right load and bullets, and can HIT where you need to at ranges things are in check with!
I personally am NOT a fan of flintlocks either, but that's a personal thing
on a side note I have seen a few come apart over the yrs and seen a few folks get seriously injured(mostly due to there mistakes)
one friend of mine is missing a thumb(has a toe where it should be now)
but the flintlock gun and caliber is up to the task of killing ab bear for sure IF you do your part right!
I Zero desire to do so with one however!