How young is too young for Facebook?

I have a Facebook account, like a lot of other adults that I know. Today I received a friend suggestion from one of my friends. She wants me to "friend" her son.

Her son is in 3rd grade. He's 9 years old. He's an acquaintance of my son.

My son does not have a Facebook account and he's not getting one until he's much older. By then I'm sure something new will have come along to replace Facebook. lol

There's a lot of things that a 9 year old boy could see on my page that are highly inappropriate. I'm not saying that my page is inappropriate, I keep it clean, no cussing, etc. However during some discussions on Facebook, there are things that are said that children shouldn't be reading. After all, this is an adult's page with other adults on that page.

Why would a parent want her young child to be exposed to this type of thing? Why would a parent allow her young child to create an account? I just don't understand this.

I am torn between messaging her and asking her these questions and simply ignoring the friends suggestion. I'm pretty sure if I point out to her that her son shouldn't be on Facebook, she will get upset.

Do you have a Facebook account? Have you ever had a friends request or suggestion from a child?