I think what she said was to the extreme but i think good parents do place a judgement on their kids friends, If i am not happy with a childs home enviornment i would NOT allow my child into that enviornment. A girl in my daughters class was very very poor, her mother usually "out of it", the guy!!! (not the kids father) was a case and a half and NEVER on the months of Sundays would i have allowed my child into that situation. I would not have said she couldnt be friends with her at school but thats where it would end.
Whilst I wouldn't allow my children in their house, had that been a friend of one of my children, I'd have happily invited her into my home. If the child was very, very poor and had an awful home life, my maternal instincts would be to show a bit of empathy, not exclude her.
I never judge my childrens' friends by their parents - if you are a friend of my children, you are welcome in my house.