But there might be something about not being able to write off illegal activities. And there might be something else about the FAA not having the jurisdiction to say what's illegal.
And that is my professional internet legal opinion. It's worth less than a cup of coffee.
I'm not sure if that violates the commercial use of a UAS, but I am pretty sure the FAA will view it as such. A better strategy might be to use the P3 for advertising without flying it. Such as mounting in a visible location with a banner hanging from it. You can even have the props spinning, but as long as it is not flying it is not in conflict with FAA guidelines.