Columbo ep. 3x2 Any old Port Q: wine cellar (Spoilers)

In the 3rd season episode of Columbo, “Any old Port in a storm”, SPOILER the plan of the connisseur brother (played by Donald Pleasance) to cover up the murder of his playboy brother is to put him into the wine cellar and turn off the AC (This always confused me) while establishing his alibi with the NY trip.

When he returns after 5 days, the brother has apparently suffocated on dry land so that he can better arrange the scuba diving accident.

Leaving aside the obvious goof (He doesn’t react to any smell; and can breath walking in before turning on the AC); leaving also aside that the main reason for this idea seems to be the Karmic payback at the end that not only Columbo catches him, but that all his prized, expensive wines have been “cooked” and are ruined:

How likely is it that a normal wine cellar would be air-tight enough for a normal human to suffocate in once the AC is off? This isn’t a tiny bank vault, this is a huge cellar as we see. Shouldn’t there be enough oxygen to last for 5 days? (Not that the brother wouldn’t be killed in another way - only that he should be still alive, even if a bit sleepy, at the return).
It also doesn’t look as if it’s airtight - when Columbo is trying the door, it looks like a bank vault door, but isn’t there a second entrance through the office? (Or was there a cut?)

Alos: maybe it’s a dubbing mistake, but several times, the cellar is called a “vault” - which is what it would be on the continent: underground and in deep rock, to keep the wine a stable, cool temperature without (before) AC. (Later, Columbo says that on Tuesday it was 40+ C outside, so it had to be 60+ C in the cellar. That’s a terrible designed cellar!)
But the shots of the door make it look like an above-ground, non-rock storage shed.

So how likely is it that in California (earthquakes so no basements?) in the 60s, a wine cellar would not be actually below-ground or in rock, but instead with thick doors and non-existent insulation?

For that matter, why didn’t Pleasance’s character drown the brother in water, and leave him in the cellar keeping the AC running to keep him “fresh”? Just because he used scuba gear doesn’t mean that he has to drown “dry” - in a panic attack, people can rip off their face mask and drown wet. Or an accident destroys their mask … (But then he would’ve gotten away with it).

I also highly, highly doubt the scene at the restaurant, where both Columbo and the secretary claim the port is fine, only for Pleasance to throw a fit that it’s ruined. Surely being “cooked” at 60 C “oxidizes” or rather, destroys, so much of the taste and flower that even moderate tasters like the two would notice it, and not only the super-refined nose of Pleasance?

The other goof at the end, where Columbo takes a cheap wine in the two liter straw-covered bottle and claims it’s a good dessert wine I blame on the props person, not the writers first.