Disclaimer: I'm not a teacher.
I think you understand the gist of the sentence. As near as I can tell, the author is saying that Johnny had many reasons to want to "get into rock and roll"; the desire to behave like a rock star (and perhaps change his personality in the process) was one of those reasons. By using the word "aspect", the author lets you know this is only one of many reasons.
On a different note, does the original text really say "exorcised"? Or does it say "exercised"? Those two words mean very different things.
Student or Learner