Having worked with R-12, I positively knew that R-12 liquid molecules -- upon release and expanding from liquid to gas -- are heavier than air. That means the R-12 molecule drops down, not up.
Having worked aboard Naval ships, I knew released R-12 was heavier than air because releasing R-12 aboard a ship tends to fill the entire hull with R-12 molecules ... pushing out air and killing humans trying to escape.
That whole “Freon destroying the ozone layer” story seemed as credible as saying “Rocks at the bottom of the ocean are floating to the surface.”