You're likely to come across plenty of words you're not familiar with throughout your life if you read enough. It still happens to me with decent regularity at the age of 36. Hardly a reason to immediately assume something is AI-generated.
He does it twice though. Maybe you're right and I just haven't read enough or I was lazy when I previously encountered that word and didn't look it up. Is it a common enough word in Europe such that it doesn't stick out there? I see that the author is named "Iain" and the site isn't exclusively catered to Americans.
Also, "epically unpleasant Iliad process to cancel subscriptions" seems equally clunky. Does "Iliad" even fit in that context?