Sure Snow Seal would void the warranty, but it wouldn't cause such odor.
I have Used SS on boots and leather for years and there was never a hint of problems such as the OP. The photos show a mess that is not a result of SS.
When you see such a mess in the top makers work please let us know.
Anyway it is a waste of time to continue to discuss this. If you want to defend the indefensible, and excuse the inexcusable then continue. I am persuaded that the maker is not up to my standards, and also that the OP did a very dumb thing.
I find it strange that anyone wants to put oil or something like SS on a custom holster. It is a case of ignorance as to what holsters are supposed to be and how to break them in and care for them.
Custom holsters are not boots that you wear in the snow.
Jerry