I was sort of expecting that reply. I've never heard of a non corrosive propellant in the world of black powder shooting.
Some are less corrosive than others, but they are also harder to ignite or have other problems when compared to real blackpowder.
Some powders use the language that they are "virtually non-corrosive". A lot of people seem to gloss over the word virtually or don't know what it means.
For a shooter the degree to which a powder is corrosive boils down to time and conditions. Powders that contain chlorates or acids may take more time to rust but they can leave serious pitting, whereas real blackpowder could start rusting the next day but is easily removed and leaves no permanent damage, because it is noticed and removed quickly.
It is best to assume that all powders are equally corrosive and you should clean your gun at the end of your shooting session.