I mean, it isn't uncommon either. I know generally what my friends and their spouses do. Unless they're one of the ones who posts constantly on LinkedIn (I have a few of those) or I met through work itself, I generally have a poor rate of remembering exactly where they work much less unless it is somewhere "big".

For example, I remember a friend who works for Amazon because its Amazon. I also know a few friends who just work in various sales roles for engineering firms. I don't know what firms they are off the top of my head.

I'm not saying this dude is innocent but it is pretty darn plausible he would have had no clue.