I'm pretty forward so I don't mind making a move on a guy if I think he's interested but what are the reasons a guy, although interested, would not take the initiative besides being mind numbingly shy?
Reason being I'm interested in someone right now and every time I make a move, I get a great response, but realistically this guy is not asking me out or starting fb chats for example. He doesn't seem shy and I haven't seen him flirt with other girls besides me.
Fear? Fear works. Then again what you mean by "shy" is "nervous" and that incorporates fear. Then there are social repercussions to take into account among other complexities that deal with core values, philosophies, and perceptions.
So in your case it's likely the latter; he's either going through willed self-restraint, pressured self-restraint, is oblivious, or has a policy that prevents interaction on such a level. Easy!
"If guys don't take initiative, it equals disinterest, correct?
He could be shy, could not know how to interact with women and taking things forward, possibly doesn't want to get into trouble with the law (he doesn't want you to press charges against him for sexual harrassment).
And he could be like I was, totally oblivious to flirting signals
No, it doesn't equal dis-interest.
You can pretend it does all you like, but you're just ignoring the possibility that the guy you like is shy afraid or intimidated.
"he doesn't seem shy"
No offence, but as a girl you're not qualified to detect a mans emotional state. In fact, you suck at it. The very evidence he could be shy (not taking initiative) is ignored by you.