Is that how you see it?
I see him as the guy who tried too hard, and worshiped that one 40,000 year old guy with god-like powers who imbued many people with extreme power and managed to accomplish some things that nobody had before. You know, because that's totally unreasonable to do. I mean, they guy said 'hey, even if I look and act and sound like a God, I'm not one so don't worship me. Gods and magic doesn't exist, and these are psychic powers not magic. totally different. Also ignore these Daemons I'm killing as I deal with hacking into this portal system of a super ancient race. They aren't real either. Oh, and you can't worship anything or I'll beat up your planet because I said so. Also genocide is okay.'
So, he created a religion based around the most powerful guy they knew, because weirdly enough, some people have spiritual needs and pure science can't always meet that, and that guy decided to respond by destroying an entire city and forcing them to bow down. Did they overreact? Sure, but you'd be resentful too. Did Emps overreact? Oh hell yes he did. He had a hate-boner for religion, that much is clear. Unreasonably so, and it's one way of showing how he was imperfect. More human. Not infallible. Closer to everyone. Similarly, Lorgar was subject to the fault of smoldering resentment and the need to worship something. Wasn't his fault, it was in his blood, literally, after all. In a way, his fall is almost as tragic as Magnus or Angron. It's similar to working for your dad as a trucker, not doing it quite the way he wanted since you have to deal with whatever circumstances and also clients kinda need to know your number dad...and so he blows up your truck with C4, chokeslams you and all your buds to the ground, and tells you never to do that again.
You wouldn't actually want to keep working for him after that.