This can be bad without invoking godwin's law.
That does not imply that fish are snakes. Nor does the presence of scaled fish invalidate the observation that having scales is a defining attribute of snakes (it's just not a sufficient attribute to define snakes).
https://www.morphmarket.com/morphpedia/corn-snakes/scaleless...
That's a strange definition of "correlation" that you're using.
Imagine there are three equally sized groups of animals: scaly snakes, scaly fish, and scaleless fish. So we have three data points (1,1) (0,1) (0,0) with probability 1/3 each. Some calculations later, the correlation between snake and scaly is 1/2.
I am noting that the logical argument does not hold in the provided definition. If “some” attributes hold in a definition, you are expanding the definitional set, not reducing it, and thus creating a low-res definition. That is why I said: ‘this is a poor definition.’