Did the author obtain the permission from IEEE to publish this work on a publicly facing internet server?!
It has a few notes about copyright at the top, which are not sufficient (at least, for me as a layperson) to determine whether this use is legal. The domain appears to be owned by the author of this paper and exist to serve all his personal publications. His Wikipedia page notes that he’s a member of one of the IEEE’s editorial boards, which certainly doesn’t mean this couldn’t be a problem, but suggests there could be some sort of special understanding.
I feel like this is a case where someone could certainly ask the IEEE if it’s okay, if they feel like it, but we shouldn’t jump to conclusions.
Frankly, I’ll happily mirror this repository. I consider it of great value, even if it is a bit shady.