Not who you're responding to but I must vehemently disagree. In English, which doesn't have a centralized governing body, the correct way of pronouncing/spelling something depends on your intention and expected audience. If your intended audience is English speakers then the correct spelling is probably octopi or octopuses, whichever you believe will cause the least confusion/distraction (surely it varies regionally).

However, usually my intention is to portray my unfathomably superior knowledge and intellect, so the correct spelling/pronunciation in this case is: octopodes (which I think he had listed but ironically got 'corrected' to 'octopuses').

"As with many modern scientific creature-names, it was coined in Modern Latin from Greek elements, so it might be allowed to partake of Latin grammar in forming the plural"

Literally from the link you provided. It was coined initially in the language of modern latin, from Greek roots, certainly, but the word objectively and literally comes from modern latin.