Two issues. The handle he used may not even be baton in the first place. That is a legal determination. Second as it relates to your question, the baton permit is valid so long as the person has a valid guard card or is a police officer.
The above information does not establish an attorney client relationship nor is it meant to provide legal advice.
A baton permit only protects people who are currently employed as a peace officer or security guard. A much better defense is that an ax handle intended for use to prop the hood of a car is not a billy.