I saw a doctor who diagnosed chiari malformation. Now he wants to do treatment. I suspect he is churning. What is significance of the condition?

Churning? Treatment of chiari malformations is surgical. These are usually surgical if the patient has specific headaches, difficulty swallowing, weakness, or hydrocephalus along with other symptoms. I'm not sure quite what you mean by churning but if you're uncomfortable with your neurosurgeon, please seek another opinion. Remember that we are here to help you and you should feel that from your surgeon.
Often none. A type 1 chiari malformation is often an asymptomatic incidental finding, where part the cerebellum in the back of the brain lies low and slips through the large opening at the base of the skull. If you've had a CSF flow study that shows obstruction of the flow of spinal fluid, treatment may be warranted. Otherwise, there is usually no clear benefit to surgical treatment.