Your meaning is not what "the exception that proves the rule" means in my experience from ~30 years ago.
In my experience, it means:
"This thing stands out to us as exceptional because it is exceptional; there is a rule which normally applies, but we tend not to notice the rule until an exception to the rule reminds us of the rule by contrast".
In my experience, it means:
"This thing stands out to us as exceptional because it is exceptional; there is a rule which normally applies, but we tend not to notice the rule until an exception to the rule reminds us of the rule by contrast".