The former captain says that's the angle at which the generator and HVAC air intakes flood. Those are closeable if the equipment is turned off. The US Coast Guard definition is "Downflooding angle means the static angle from the intersection of the vessel's centerline and the waterline in calm water to the first opening that cannot be closed weathertight and through which downflooding can occur."

So downflooding angle safety certification for bad weather apparently assumes the boat being in a buttoned-up condition. But, buttoned up, the yacht has no air conditioning or non-battery power. One article mentions that lowering the moveable keel for more stability results in a much noisier environment below decks. So, rigged fully for bad weather, it ceases to be a luxury yacht.

The ship was in harbor, at anchor. That's not usually a situation in which a ship is rigged for worst case conditions.

Here's a picture of the infamous mast.[1] It's not just a pole. There's a lot of structure with surface area. Nobody seems to have anticipated that wind on the bare mast system was enough to knock the boat down. But it was.

[1] https://www.msn.com/en-us/money/markets/how-the-defining-fea...