Well, lesson learned, then -- people get upset about this stuff, and sometimes even sue.
Now that he's posted an apology, I've come to believe that Pauxcore just didn't know that this kind of thing is very much frowned upon in the design community.
Pauxcore -- don't view your efforts as wasted time. Now you know how to create a theme, and can make one using your own designs.
I apologize in turn for reacting harshly, and commend you for realizing your error. You seem like a sincere person who simply made a mistake.
You can avoid this kind of reaction by taking a little time to understand the issues of intellectual theft, copyright, and the various kinds of licensing regarding digital design and the internet. Everyone borrows and learns from everyone else, but copying an exact design without permission is crossing the line.
And when you do borrow something significant (such as bits of CSS or other code), it's common courtesy to credit the original author, at least in your code.
When you come up with some original designs -- as I'm sure you will -- come back and share them here. People here are generally supportive, so you shouldn't feel that you can't share future designs here.