Bringing a guillotine to a protest merely to show it off and make a statement is a great way to have blackshirts (also known as the police) harassing you about making "terroristic threats".

Cutting fruit with it sends the same message, while also demonstrating that the device actually works and is not for show. And you have a legitimate reason for having it. What, officer? I'm not threatening anyone with this. This is a watermelon-cutting machine.