This isn't an age issue at all.  If he was raised that way, he'll probably stay that way.  You can't change people nor make them change.  If she is having these issues, it's his personality/background not how old he is.  Good luck.

Even if your point is agreeable you made it known to her already and now it's best to let her handle the rest since it is her relationship. Sometimes people have to find things out the hard way.

I'm glad this article isn't saying it's the fault of the young (and blaming gender) :) I do think a big factor in what could be a good couple for the long haul is often age and timing. I think it can be hard when people find love very young and hard to work for good. It can happen, but it makes it harder. There's no way to know how long it will or won't last though. 

I understand that you want to help your friend, but she already knows what you think and will only listen to what she wants.  If I were you, I'd back off of her boyfriend issues unless she brings it up.  What is the term?  Beating a dead horse?  It's futile.  And you're right, people won't change until they want to change.  Sally probably figured she can mold him into the perfect man because he's younger and more impressionable.  He's already grown, he will choose for himself, regardless of what any woman tells him.  Best of luck to your friendship with Sally.

I don't understand what this has to do with young love. He grew up in a troubled home. His issues aren't because he's 4 years younger than her.

i know this is a very old post but figured i'd comment on it anyway seeing as how i can relate and if anybody stumbles on it with the same problem, maybe i can be of some help. 

the guy i'm currently seeing is 19 and i'm turning 23 later this year and in all honesty, it's one of the most compatible pairings as far as my track record is concerned. and not because i needed to feel young, or because he refines the idea of love with his innocence, etc. i didn't even want to get into anything with him and resisted for months but he pursued me avidly and showed genuine interest. and i'm glad i finally gave in because i truly get along with him. yes it's fun and refreshing but every new relationship is. but i can hold actual adult conversations with him, share with him, be myself with him. this might be a person specific trait, of course there are still 18-20 yr old guys who are as juvenile as ever. i mean forget that age range, some guys in their late 20's are still stuck in the long gone teenage years. point is, when you know, you know. the age difference is no longer a factor with us. and i think this is where her friend was at at that point as well. 

with that being said, i don't think his age had much to do with the fact that he was evidently racist. it's not like that's something you grow out of, that's a personal prejudice that a person develops themselves. and sure he might be younger than her, but he's still at the age where he can think clearly or objectively, and make up his own belief system.
for anyone wanting to approach their friends with a similar issue, i suggest you don't keep pinpointing his age, and hovering (even subtly) around the fact that he's younger than her because trust me, i had a friend who tried that in the beginning stages, and even though i knew she had my best interests in heart, i did not, and i mean did NOT want to hear that. approach the conversation from a completely different and relevant angle. in this situation, it'd be by asking her if she's aware of some of the slightly archaic beliefs he holds and if she's truly okay with it. if she's falling for him, clearly he was doing something right.