As one of the people who blew this "out of proportion," I'll first apologize (I am sincerely sorry), and then attempt to explain myself.
As I said, I'm a SCUBA instructor, so I believe that I have an understanding of the dangers involved. I don't believe you can be sufficiently prepared for an open water dive (and take said dive) in four hours. I don't believe it's safe. I offered my sincere opinion and advice. I apologize if you took it as an attack on your character. It's been my experience that if, after taking one of these one-day sampler courses, you then take a proper course and become certified, you'll be horrified that you went into the ocean after so little instruction.
In the end, do what you feel is best. You do not need to justify yourself to me or anyone else on this board. And again, my apologies.