I suspect your analysis is right. I think if someone wants you to go away, they are generally vague ("I'm really busy now, this is not a great time") whereas if they are more specific ("call me after next Tuesday") it is probably legitimate, but they are either disorganized or very busy or psychologically complex as you describe. I would continue trying for a little bit if you do want to meet him, but know that this annoying characteristic of his will probably not go away in the future.

However, it sounds like just calling won't work, or at least won't work immediately. I would suggest getting out of the game by manufacturing some time-dependent invitation. Perhaps a mutual friend can invite you to a dinner party? Perhaps there is some work-related event (a conference, a talk...) happening that you know he would be interested in, so you can suggest going together? You say it's for "work/study," surely then you have lots of deadlines. Perhaps you can call to ask his advice before a specific upcoming deadline, and this will force his hand a little.

Good luck.