A legal-minded FrontBurnervian says the prankster may have a bit of trouble in his future:
Sorry to get all legal on you and stuff, but what the guy did arguably violated federal laws which criminalize impersonation of a US official.
Â§ 912. Officer or employee of the United States
Whoever falsely assumes or pretends to be an officer or employee acting under the authority of the United States or any department, agency or officer thereof, and acts as such, or in such pretended character demands or obtains any money, paper, document, or thing of value, shall be fined under this title or imprisoned not more than three years, or both.
The government could argue that the thing of value that was obtained was the venue for and opportunity to make his speech. And there very well may be other Louisiana or federal laws he violated.