If you weren't the one responsible for moderating at that time then I'm not blaming you. I'm blaming the guy who was supposed to be moderating at the time of the report. 9:30PM isn't particularly late and I would have assumed you had had a US-based moderator for a US server.
Regardless of what happened if you aren't able to find and ban the guy now then you might as well lock the thread, doesn't seem productive to keep arguing.