Gao Guang wasn't someone who spoke without action. Once he brought something up, it definitely meant he had a complete plan in mind.
We've been through thick and thin together, you save me, I save you—such things need not be mentioned. But just because someone's disabled doesn't mean they're done for. Gao Guang was willing to help Fang Zhenwu back into the saddle for part of the journey, and there was no way he would shortchange John.
The only thing was, Frank hadn't originally been part of the plan. That was only because Gao Guang didn't want to disturb Frank's retired life. However, now that it had come to this point, gathering Frank and the others was entirely possible.
John had probably lost all hope for the rest of his life. He was ready to just idly wait for death. But now, finding out that Gao Guang had paved the way for his future, John's spirit quickly picked up again.