I know. It seems so obvious That's how I see it too.
The way the sign is currently worded however, leaves room for less lenient interpretation. I just wanted to make sure the majority of you felt the same way, because the way I am going to phrase the sign to Mr. Wilson is that we envision it as a set of agreed upon guidelines or recommendations to promote safe kiting. I am just covering my butt before I present our idea. I want to represent the consensus. At the same time, I personally feel if that is our approach, the sign should more clearly represent our intent through it's phrasing.

Must, for instance, can't be used verbiage. It implies a possible fine or consequence from the park if disregarded.

Most signs (think about this) especially in a park, tell you what you can't do and have the backed up authority of the "head cheese", with a possible fine usually. I was probably pointing out the obvious. But maybe not.
Since so many hopped on and agreed with the obvious, can we then agree to change the wording to use more terms like - recommended and encouraged? This helps to strip a lot of responsibility off of Mr. Wilson and puts it back on us to use peer pressure and conversation as persuasion for riding safely.
The sign (although not a legally binding and enforceable list of rules), is a testament to what our local community agree are some safe kiting practices, and as stated, shows we aren't a bunch of yahoos. I think it'd be great to get it out there.