Word for falsely declaring something an anomaly, when it is actually typical?

Is there a term for incorrectly distinguishing something to be not part of a common category of items, saying a sub-group is too unique to be considered to be part of the larger category, even though almost all of the facts presented are true of the larger group?

E.g. To someone who says “A Sanguinelli is not an orange; it is too sweet, has seeds, has an orange rind, & the red inside proves it is not an orange.” (even though you dispute it is a type of ‘blood orange’ is conducting a ___.

A term for a person who does this can also work.

I could not find it in a list of fallacies, so I created some terms that estimate what I am trying to express:

• False Un-Equivalence
• Incorrect Anti-Generalization