Kids shouldn't nip in bud. Many parents doesn't allow them speak their words and as a result they never can be confident in public to express their thoughts or valuable opinion. Its true sometimes kids don't know what to talk and talk what we don't want to expose or prefer to keep hidden. Kids are innocent and they mostly found saying things they listen and they learn.
If kids can't express themselves properly they never can be creative and become introvert as a result they can't update themselves with the current world and it surely not good for parents as they are always concerned about the future of their kids. Let them learn what is good and what is bad and you shouldn't teach them that by scolding them in public or private. Deal with kids with love and affection as they really need of this.
Parents try to teach their kids in front of others and they usually don't take it positively. Teach them in private and let them express and talk. I'm not a kid's psychology expert but there are so many things we can learn from other's and from our own stories too.
Once there was a five years old girl who loves to talk, sing, dance and express herself but she was nip in bud and always stopped by parents and siblings and later she found herself nervous in public, she always had shaky voice in public and debate function, her voice and body both start shaking whenever she attend any public function. She often scolded by her parents and siblings in public and now she is no more confident to express herself because she is scared about people and always scared that how people will react when you will express herself. I'm the witness of this story.
So I request to all the would be parents having a course or counseling on parenting which can save your child or children from being nip in bud. If your kids talking nonsense let them know in private or tell them a story that they can get a lesson from it but do not scold or abuse them which can affect their brain and it may works in a negative way in the future. The future of your child is on your hand. Please let them speak and let them explore.