Fair point made with regard to "you are a certified diver and responsible for yourself." The conflict for me was that my last instruction from him was to stay where I was, so I wanted to follow that instruction. I think in future incidents I will be less likely to give that much weight to my instructions and decide that thinking for myself will take priority much sooner.
Every dive and ESPECIALLY during training dives we explicitly brief a "lost buddy" protocol.
The standard protocol that PADI teaches is to search, once separated, for 1 minute and then surface. I discuss this at length in the theory and we actually practice searching in the pool (keeping track of time and then surfacing after a minute).
During training dives, what I tell my students to do if they find themselves alone is to wait where they are for 1 minute and then surface.
The reason I brief it this way is for practical reasons. It's because *I* know every grain of sand at the sites where we train and students are often seeing those sites for the first time. So when I realize a student is unaccounted for (thankfully this very seldom happens) I know EXACTLY where I saw them last. Chances will be 99% that they are just outside visual range (we can have horrible viz) so I can find them almost immediately as long as they stop moving.
The fact that your instructor didn't tell you something alone these lines is why I said he/she was being sloppy.
The other thing that made me think, "sloppy", is that he allowed you (or even TOLD you) to settle on your knees. There is a paradigm shift happening in scuba training and it's becoming less and less common/acceptable to put students on the knees at any time. In my own case the my students only do a couple of skills in the entire OW course on the bottom of the pool and they don't touch the bottom again after the second lesson in the pool. To me, putting a student who was doing a drysuit course on their knees would be completely unthinkable.
I triggered on that for professional reasons but the safety issue of not briefing a lost-buddy protocol is a much bigger deal to me.
I mentioned the firefighting thing to illustrate that I'm used to being in zero visibility situations. I'm also trained to NEVER leave my team. Ever. Ever.......EVER. If separated, the priority is to re-assemble the team, not fight the fire.
It is similar in diving, but the ocean is very big if you don't know where to look so reassembling the team happens on the surface.
Also, and perhaps most importantly, if you ever are separated from the team, you STAY PUT and let them find you (unless in immediate danger). I guess that muscle memory kicked in yesterday.
If everyone stays put then nobody will find anybody. Someone has to be looking. That's why I said I brief things they way I do during check out dives.
R..