There's a third option: he doesn't know and didn't care how to write the words. I'm neither British nor American, but was taught British English on school. Most of the internet uses American English. I couldn't care less I type "optimised" or "optimized", and I'm pretty sure I've used different spellings for the same word once in a while too. I see no reason to assume Satoshi would use perfect English without mistakes.

Or all 3 options could be valid at the same time.