With a 5-year lifespan for an LEO sat, that's potentially 120,000 deorbits every 5 years...
That will add up quickly... I don't know the science of aluminum oxide increase to ozone depletion.. but this can certainly warrants more research and consideration
1: https://starwalk.space/en/news/spacex-starlink-satellites-ni...
Does the mass make a difference?
NOx is also has a global cooling effect, taking the edge off climate change.
NOx and VOCs from power plants and diesel vehicles produce ozone.
Any exercise in making numbers out of nothing is completely useless.
(Besides, is chlorine activation really a bottleneck in ozone depletion? AFAIK it gets activated by UV light quite quickly.)
More fundamentally, chemical catalysts by definition are not consumed by the reactions they catalyze.
Think: a cheese grater. It doesn't react with the cheese, so a few ounces of grater could make hundreds of pounds of grilled cheese.
A hypothetical 300 tons of catalyst is not limited stoichiometrically to how much substrate it would affect.
For example, consider that a car exhaust catalyst contains ~5 grams of platinum, and AFAIK, that doesn't really "wear out".