So, I'm going to give Geoff Johns the benefit of the doubt that this is a joke (click to enlarge):
Because the idea of "Sinestro" being an alien word with undecipherable meaning is pretty hilarious. Stuff like this reminds me of the short-lived Fantastic Four cartoon a few years ago, where they end up in the Negative Zone and meet Annihilus, and Johnny cannot contain himself, saying over and over to Reed "Ask. him. his. NAME!" and then basically giggles through the entire episode.