One man’s incorrupt does seem to another man’s not incorrupt.
While St Bernadette’s body is amazingly preserved that phenomenon alone would not appear to say anything particularly special about the Catholic Church which I gather is what you may be implying.
Actually she has been significantly touched up, her body has been “waxed” and her face is a “mask”. She is in a hermetically sealed glass container with oxygen removed I believe.
Her nose has been extensively repaired as it had partly corrupted.
I believe the same is the case with one of her limbs.
I believe her original coffin was hermetically sealed in a lead lined coffin and kept in a vault and not in the ground.
The Buddhists also have a tradition of their holy ones being incorrupt and kept in glass cases.
When the motorway went through the cemetery in my area in the 1960s all coffins were relocated.
The papers noted that a couple of the bodies had not decomposed.
It appears to be some sort of “natural” phenomenon.
I am not sure everybody would agree that “atrophied”, “shrunken”, “sunken” and “dessicated” is what most would understand by “incorrupt”.
This appears to be a balanced treatment:
https://www.osv.com/OSVNewsweekly/S.../13567/ArticleID/9570/The-Incorruptibles.aspx