I rarely use code folding. Furthermore, few people other than programmers use code folding.
Not knowing the copy and paste keyboard commands is a completely different realm of incompetence!
But you're right that lots of developers don't know many keyboard commands. I was being a bit too broad. Personally I can't imagine how any programmer would not bother learning keyboard shortcuts (or even better vim keybindings), but I've met plenty who didn't.
It seems odd that someone would not know the copy/paste keyboard shortcuts, but the most likely explanation is that he hadn't figured out that it's Command+C rather than Ctrl+C on the mac.
That being said, while using the 'edit' menu to copy/paste is clumsy, I don't see that it would actually have a significant effect on someone's productivity. So I would not go so far as to say that someone was incompetent just because they did that.
Hell, I spent time stuck on a problem because I had never used code folding before, and couldn't find the import statements I needed to edit.
Would you agree that not understanding code folding is a bit much?
I'm not defending the particular individual, or the situation, only giving some context to my comment.