Argument by association. One of the weakest forms of argument.
When saints are buried, no one asks for them to be made incorruptible. They are found later, some times hundreds of years later. It is a sign, for us to study and imitate their life. But it is not a sign we asked for due to disbelief.
Your arguments that all incorruptibles can be explained by natural causes is what atheists use. Sorry if I assumed you were not a believer in Jesus Christ.
As is the general case there really is no way to convince someone who ‘wants to believe’ in untruths .....they can’t get beyond what they’ve been indoctrinated to believe.
Fro all I’ve seen and noted any religion can create relics and various other tricks of their trade to keep people engaged. There is a difference between ones faith in a person and that of objects and dead corpses...no matter what they look like.