Aristotle (the ancient one, of course) was emphatically not an "atomist." He roundly criticized both Democritus and Leucippus.
That is correct. Also, Aristotle more or less invented scientific taxonimy, like the system of phylla, genres, and species, which is probably closer to the true inspiration of the OO "description of the universe". From that standpoint, Aristotle would be "Platonic" too.
I however think that this is really a great topic, because it seems obvious (and significant) that programming languages are subtly based on traditional Western logic and ontology.