That's a perfect translation, though. The joke is that Seishirou used a really new and memey word like おこ in the middle of his otherwise quaint samurai speech. Araragi explicitly mentions this.
It doesn't matter - the point is to farm for replies, even ones such as yours. Many people on /a/ are more interested in freaking out about things than actually talking about anime.
I liked it a lot. I get really happy when the manga actually gets updated. That said, I still found that ED translation to be pretty funny and it was only on the final episode so it was no big deal.