I'm not sure that your conclusion of "God is justified to allow moral evil" holds.  Take the situation of an invincibly ignorant person, who has no access to Judeo-Christian revelation, and is trained in a society that contradicts Judeo-Christian morality.  As an example, Carthage was described as practicing child sacrifice.  The "moral" choice for a member of that society was to have their child roasted to death on a heated bronze statue.  Why would a Just God allow, even force, someone who knows no better to "murder" their own child in such a horrible fashion?  There is a forced evil to the parent's decision and evil's consequence is inflicted on the most innocent of victims.  "Free Will"  seems to be negated in this situation.

I don't think that the problem of evil will go away or be solved. given the limited nature of human understanding and our lack of knowledge of how God actually made this existence.  The problem of evil is simply a mystery beyond full understanding at this time.