I think the biggest thing that bothers me isn't the fact that he copied so much, it's the fact that he didn't acknowledge everything was inspired by DF until someone brought it up in the comments. That seems a little underhanded to me, and it gives the impression that everything he has on there is original and made by him. That not being the case, he's pretty much being dishonest.
But I have to agree that if something good comes out of this, more power to him. I just dislike how he displayed "his" new creation without even a mention of what it was copying. I think that's the main reason everyone's getting overly dramatic, here, not because some guy decided to copy everything about DF, slap on some graphics and post it on YouTube. He passed off creativity as his own (Or appeared to) until accused of copying.
If he had made the video title, "Game Test (Inspired by Dwarf Fortress)", then I wouldn't have a problem with it. As it is, he made up a name for his program and doesn't even mention DF. Bad move, even if his intentions were/are honest, and he's basically screwed himself over if his intentions aren't honest.
We'll see how it plays out, or if he even keeps on working on his project.