This is kind of that 'climate change skeptic' argument that CO2 is only a tiny percentage in the atmosphere, 0.04%, so anything humans have done to that tiny percentage is therefore negligible. But we've had a massive impact by increasing that tiny percentage by 50% causing climate change.
So the starlink satellites dissipating could increase the aluminum oxide arriving up there by ~10% - depending which numbers are correct I suppose it could be anywhere from like 3-30%.