Earlier, you said something interesting: It doesn't presume that the young man was now a saint, ... only that he was now moving in the right direction.
An honorable act must be based on honor or else it's an empty gesture. I don't see it in the intent of the younger son. I wouldn't call it the 'right direction.' It's called opportunism.
You're opining on motives.
Even if there was anything other than opportunism mixed in with the young man's motivations, ... it is a start.
His father now has the opportunity to teach honor to his son.
There was no chance of this so long as he was in the world.
By throwing a party after what he has done? By neglecting his older son's honor and obedience?
This is the kind of liberalism that doesn't correct bad behavior, but only makes people 'feel good' about their bad behavior. No wonder we solve nothing with this approach.
A good start would have been to turn down his father's offer, ask for a conditional return as a servant until he had earned enough to pay back his father with honest work, and then to ask his father for forgiveness.