He may be annoying, for whatever reason.
And there may be natural consequences.
But the teacher's job, especially in such formative years as kindergarten, is to not only help your child navigate appropriate social interaction with peers, it is also imperative that she teach your child's peers appropriate responses. Telling a child, "I don't like you" may be normal, but the teacher should be correcting the group by teaching them better communication techniques. I.e. "When you knock over our blocks, we don't want to play with you." That is a very different message that is better for your child to hear, because it gives him something concrete to work on, and it is better for the other kids, because they learn to draw boundaries appropriately.
