I don't think you'd get very far with such a definition for any other -ism. Moreover, we do things like attempting to wipe out entire organisms (e.g. malaria mosquitoes) simply based on what the average one does, whether or not any particular mosquito would have bitten a human.
So you'll have a hard time unless you add lots of special cases to it.
>And all such distinctions are, by definition, 'speciesist'.
not. Recognizing difference in sentience level not necessarily means "specie-ism", for example between a human with severe autism and a "normal" human.
And all such distinctions are, by definition, 'speciesist'.