It also demonstrates what is a safe speed in wings level might not be safe with any bank on the plane.
I'm not saying it was unsafe. If I remember correctly, the stall horn goes off 5 to 10 knots before stall and since it was barely starting to go off before Chuck corrected I'll assume it was closer to the 10 knot figure. I never took a mountain flying course and I haven't flown GA in 14 years. But during all my training and as a CFI getting a stall horn before the flare was not normal or considered within acceptable maneuvers tolerance for any landing maneuver. Getting slow and low in a base to final turn was the killer stall example that was hammered into student's heads to never allow.
I don't disagree with your points. I'd also offer that different flying regimes, along with different airframes, yield different requirements. I know that's not new news to you, just stating a preface. As an example, for short fields in high DA, flying 1.3 Vso won't work, and instead flying MSA (in a precision manner, of course) is a better approach. And yes, I get that MSA requirements have changed, as previously the PTS (or whatever it's called now) said you could have intermittent stall warning, it's now changed to say keep it just above the warning.
And this isn't meant to counter anything you're saying, just pilot talk here... Some planes are way more sensitive to approach speed than others. Historically, it was a big deal for my plane, and the issue was people would fly it like they learned how to fly a 150/172. That is, they'd fly some sort of approach speed and fix it in the flare. My plane is much more sensitive in that a fast landing can result in porposing and prop strike, which is why it got a bad reputation in the past. As it turns out, it's very docile, you just have to actually fly it correctly. As a result, it's not uncommon to get a stall in the flare with a very smooth touchdown.
Again, I don't think we're in disagreement with the overall intent. I just come at it from flying something that absolutely required you to be on-speed from the base turn to touchdown, and if you got aggressive with it (not in a bad way) or you got bumped around in turbulence, the stall horn sounds and it's not the end of the world.
Hopefully I'm conveying that this would be a good pilot discussion over beer and not as a counter to your points.