It’s true that slip-ups like this can be revealing. But people do use cockroaches as examples of very primitive creatures. Racists also like comparing ethnic groups that they don’t like to cockroaches (especially when complaining about their proliferation). So CP was very exposed to the sort of attack you did, which is why it hit a nerve, I would guess. (Had he used monkees or apes for the analogy he would have been in the same situation.)