Correct. Facts are facts. You have a bunch of people from shitholes, loaded with diseases nearly eradicated in the western world, waltzing across the border. Gee. I wonder why we have flu strains from South and Central America. Must be water vapor from jet exhaust.
Look… I get it… people who aren't aviation enthusiasts don't understand how air temperature can change radically throughout altitudes, how varied air pressure can be, and what that has to do with the condensation of combusted fuel on soot molecules. It all looks really weird when planes flying at indistinguishable altitudes have very different exhaust condensation patterns.
However, a little protip. Ultraviolet radiation - which our sun releases a lot of, is a very powerful antimicrobial force in this world. If I was going to deploy an aerosol bioweapon against anyone, I would do it within the troposphere, after dusk. It would be an invisible dust - the consistency of smoke particles - and would travel on the wind.
It would be the height of stupidity to release any organism, or organic molecule, into the stratosphere with the intent of it reaching the ground. The UV would destroy the package, it would take unnecessarily long to reach the ground (as in, most never would), and would generally be a complete waste.