Ron, I don't know if hydraulic oil is worse to breathe the fumes than Corvus or engine oil, but it sure smells worse. One of my planes has hydraulic oil powered gear and a small leak stinks for a long time. The engine oil leaks don.t smell great but not as bad.
I don't know what you mean about smoking dangers "not based on science". Certainly the dangers of smoking, first or second hand are well proven and have been for years, Even tobacco cos don't argue about it anymore.
Lung cancer is not a myth or opinion , its a fact.
Sometimes airshow oil smoke seems to disapate int the air, but sometime if the wind is wrong it blows right on the crowd. I"ve seen planes take off with their smoke on and really soak folks and planes nearby. Saw one, probably a CJ or similar do that departing rnwy 9, blew right on the controllers, marshallers and other planes waiting to take off.