I like your utility-exchange idea. That explains the problem of why Quirrel isn't seeking power in his own right - because to do so is to inevitably hand power over to the Dark Lord. Hence, he seeks to fashion a better and uncorruptible replacement. Power wouldn't necessarily help him find or groom a protege.

The utility function exchange might be going too far. The trade might just be one of the classic 'loan' or Faustian bargain: Voldemort lends his accumulated skill and knowledge to Quirrel for 15 or 20 years, and in exchange, Quirrel hosts Voldemort (as he did in canon!) and at the end turns over his body to Voldemort and/or merges with him.

At least, this seem to work as well to explain the issues (if there has already been a utility exchange, how have Quirrel's values changed?).

For just his political views and most of his behavior, being Voldemort is not the simplest explanation.

My problem exactly.