Punishing a child in kindergarten because homework is late is just wrong. I learned how to paste in kindergarten. Last year my daughter learned about planets, how to read, add and subtract. Wow, times have changed.
I don't think that the teacher was right to exclude your daughter. I can only imagine what she felt like. Not only feeling bad, she probably did not want her new friends to think bad about her.
I was so lucky with my dauthers kindergarten teacher. She was very open, friendly and understood everyone had different situations.
A child this age should not be punished for homework. Several times my daughter turned her homework in late and she was never punished. The teacher felt bad that she did not have it when the other kids turned it in. (her dad and I are divorced, he never did her homework with her when he had her. I was the only one who sat down to do homework with her. I am very gratefull that the teacher is understanding of our situation)
I would definately talk to the teacher. If you don't get what you want from her, go to the principle.
Is there another kindergarten class she can go to? She will still be in the same school with the friends she already made.
We sent our daughter to our local park district. They have a private kindergarten that is outstanding!! She learned more there than she would of in a public school.