I was using the term "mental retardation" in a more literal sense vis a vis a literal slowing of the mind, a dampening of the intellect. Which is the chemtrails conspiracy generally (mind control of sorts), and honestly what I (mistakenly) thought you were alluding to with the "people who need to be aware of it" remark. Cloud seeding is a more recent addition.

We'll say 100 grams of seeding material per spread

I have no idea where you got that number, but first, a quick Google on the silver iodide (preferred cloud seeding material) required on a typical seeding run is 25-100kg, or 25-1000x what your estimate is. Give that AgNO3 is 234g/mol and Al2O3 is ~102g/mol, you get the same number of Al2O3 particles at about 1/2 the mass expense, so 12.5-500x your estimate for the same effect. Either way, adding kilograms of effectively-pulverized-sand absolutely introduces the polishing effect.

Second, even if 100g per run in a 737 means 100g dispersed over some 3,000+ miles, so 33mg/mile at best, which comes to about 6 micrograms per linear foot. If that's cloud-seeding density, I should be kicking up thunderstorms every time I polish my tailpipe. No, that's not a euphemism.

You talk about surfactants... that's on the right track, but you were a little closer with the nanoparticle idea. If you conjugated the Al2O3 with a soluble chelating agent or packaged it in a more soluble nanoparticle, it could protect it and the engine parts through combustion. At which point, maybe the nanoparticle shell degrades in the high temps of the jet engine exhaust, exposing the Al2O3. It would be a pretty cool chemistry achievement honestly.

But you'd probably be better off working with some other cloud seeding agent.