Propane is a very good refrigerant for many common uses like AC, heat pumps, or refrigerators, yes. But yes, AFAIU initially CFC's were hailed as a significant safety advancement and quickly replaced older refrigerants that were poisonous (ammonia) or flammable (hydrocarbons). But subsequently we've become better at making refrigerant machinery that needs less refrigerant and is less prone to leakage, and the natural refrigerants have made a comeback as subsequent generations of the flourocarbon family refrigerants have been banned (CFC bans, F-gas regulations etc.) and become more and more expensive.

> It's widely used in commercial units.

That right here is the point. With commercial units, you can be relatively sure only trained professionals will touch it, it will be somewhat decently maintained, and installation will be done with decent quality. With anything consumer-retail? As a manufacturer, you'll have to include absolutely ridiculously dumb people into your risk estimation, and you don't want to risk headlines like "Exploding brand XYZ AC unit kills family in house fire" because the father who had installed it caused a leak in the propane circuit - people won't care about that distinction, they'll see your brand as tarnished and unsafe.

Don't forget decades of advancements in manufacturing procedures, engineering, tighter tolerances, improved materials science, and so on that have happened to help ensure the propane remains in the coolant circuit.