Hi WolfPack,
Lots of good advice, and I will have to second some of it. I hate it too when staff at the
LFS try to sell you something, and lie about things just to get you to buy it. Frustration aside, I would either tell your friend to get a much bigger tank, or remove the tinfoil barbs. The angelfish, like everyone has been saying would be okay, but only one. Angelfish can grow much larger than their average if kept properly, and develop quite a personality, and even become attached to you.
Good luck to you and your friend!
Ali