I must be reading your note wrong.
If a CW session(s) can be accomplished in a real body of water, why wouldn’t an instructor take his students there?
I’m proud my CW sessions were in salt water.
I’m not against a pool session but if real water is available, I say ‘crack on’.
The key is that the definition of confined water needs to be met: pool like conditions in terms of depth, clarity, and calmness. Note that temperature is not there (a good thing). I have found that the contrast from a pool to the cold, dark Puget Sound with much bulkier exposure protection has been a significant stress factor for many students. I had a student that had a fear of childhood of the dark water. Unfortunately, no one elected to tell me this (so I now ask about any such concerns), including her father who took the class with her. Needless to say, she freaked out when we were to descend down the line for OW1 and I was glad I had 2 DMs as I lost one who towed her back to shore.
There are some shops in the area that do use protected cove areas in the Puget Sound. I think in terms of calmness and clarity, this is really pushing it. There are some locations in the larger lakes at certain parts of the year that meet the definition of clarity. But that's between them and their agency. There are some parks along Lake Washington that are absolutely perfect on non-windy days, but only September through March.
When I open my dive op in Greece, the confined water we use will be protected coves. The islands are not small, so I can always find a shallow, protected cove on the leeward side of the island. Clarity, check. Calmness, check. Depth, check.
Real water is nice, but it needs to meet the criteria. I can imagine your experience in the Red Sea was a perfect transition to the conditions for the open water. I'm guessing your confined water was a place where you could stand and if you kept walking out, you'd get over your head, and that it was protected and/or there just wasn't any wind. Double thumbs up.