Identifying the nature of Joe and Oliver's hindrances to emotional and relational freedom in terms captivity was only the beginning. It's also important to connect these revelations more specifically to how they contribute to the events of Lost Without You.
The only way to correct Oliver's seclusion, and Papa O'Toole's wandering, was to expose each man to that which they spent so long avoiding. That's exactly what happens at El Dorado Canyon.
No question Oliver has emotional and relational wounds in desperate need of healing. These wounds comprise the "cage" in which he's currently trapped, so the only way to break Oliver free from the "cage" is to find a way to heal the wounds.
It's clear Oliver knows he has a problem---Montaldo's and its aftermath proves that---but he can't figure out what it is, or how to truly resolve it. Not coincidentally, it's the one place Oliver is dead-set against returning to that holds the key to his freedom. Oliver must "[go] back to the forest"
because its where he became confined to the "cage," and it literally takes an act of God for him to finally return.
Unlike Oliver, Joe is seemingly unaware that he has a problem that needs resolved, despite the fact his migrant tendencies suggest otherwise. In fact, he's done a pretty good job of running from the pain over the decades, a "cage" in and of itself. Because of this, Joe had to be "laid low by a scratch"---physically prevented from running away---so that the source of his pain might finally be revealed to him and given the chance to heal.
Like Oliver, Joe's wounds were incurred "off trail" that day in the forest, the puncture wound a reminder of the pain he has spent decades harboring unresolved, both emotionally and spiritually. It's these areas which his wilderness encounter ends up addressing simultaneously. Joe's repeat encounters with instances of abandonment at the hands of his wife, son and even Curly caused him to drift both physically and spiritually to the point of peril, but it began that day in the forest.
For both men, freedom was only possible by returning to the place where they became captive, retracing their steps on El Dorado Canyon decades later. By confronting the emotional and spiritual wounds Joe and Oliver spent so long avoiding, they created an opportunity for healing only possible by coming to terms with the events and consequences of that day in the woods.