I took that quote from that presentation. He hates all OO code, so it's not specifically Ruby that's the problem for him, but object orientation. His point, however, is that being able to reason about your program is important. That is also a driving factor behind DCI. OO programs often hide exactly what happens among objects because we mostly see everything from the perspective of a class, rather than a perspective of being among the communicating objects.
I'm not sure that he broadly hates object-orientation as an idea. It's true, he hates much of the conflation that goes in OO (E.g., conflating classes with namespaces, objects with data structures, encapsulation with object ownership, and identity with state). And he hates the reliance on tests to overcome that conflation and confusion--something that's hugely prevalent in the Ruby world. But he does allow most of the features of OO in Clojure.