First of all, you do seem to be looking for an argument or at least are being condescending because you ask a question, one I answered and then you basically tell me I am wrong.
Now onto the actual law, you are being quite liberal with your interpretation of the law. You are reading "dive tourism" and thinking it refers to a business. Any diving in Bali by someone who is just visiting, is considered dive tourism. Also, you keep mentioning snorkeling and no one here as mentioned that. This a post about diving on a message board with SCUBA in the name.
If you rent a cylinder and weights from a dive op, you are now partaking in diving tourism and as such, would need a guide. Every dive center here knows that the law exists. Do they all follow it? No they do not. Some places will let you rent cylinders and weights and go for a dive with a buddy. Many won't allow it. I prefer to stay on the right side of the law these days, not so much when I was younger, therefore our dive center will not let you go out without a DM or myself accompanying you.
Yes, it only applies to diving tourism. Any diving a non-citizen or a person without a valid work permit or retirement visa does falls under that stature. You are a tourist engaged in diving activities, hence dive tourism.
All recreational dive tourism activities in open water must be assisted or supervised by dive guides or instructors from dive tourism entrepreneurs (If you dive in Indonesia as a tourist, you must be assisted or supervised by a guide or instructor from a dive center or dive tourism business)
I hope that helps.