Overview
A colleague of mine requires a work visa to work in the U.S. My colleague and I work for this nonprofit organization currently. We first worked at this nonprofit as interns 3 years back but I managed to find a different job while my colleague is now working as an employee for this nonprofit because they are the only one who are able to offer him a work visa currently.
The nonprofit has a project they have hugely invested time and money for 3 years on. My colleague and I are the birth creators of this project and worked together back then. The project is at the development phase (which is where the organization's budget is all being spent on) but has run into major progress and management problems, where the chance of failure is now high.
My colleague is the current main lead for the project. I am currently playing an adviser role for this project and have no contract obligation to them, meaning I can leave at any time (the project is a small learning benefit to my career but it's not my day job and I don't care about the nonprofit).
The problem
The nonprofit has become a significantly toxic place to work in and my colleague is feeling extremely frustrated at all demands and overwork the CEO is giving him. The reason for this is that he is the only true paid employee left; every other paid employee has quit and there are just temporary volunteer (part-time, inexperienced, unpaid) staff remaining. As such, in addition to leading this big project, he also has to do all other tasks that the other previous paid employees did. This led to the project management problems.
He wants to quit but he can't because of his work visa. He is currently looking for another job and has no success so far.
He and I are the only people who are still at this organization with the highest depth of knowledge of the project. In other words, if he and I leave, the nonprofit will crumble as no one else will have the knowledge to be able to take over and all the budget invested on the project will be wasted. It's not an over-exaggeration if I said we are quite legitimately the organization's lifeline.
As such, we would have the upper hand advantage but my colleague's work visa means he is stuck there if he doesn't have another job lined up.
Question
What can I do to best assist him right now in this situation? Also, if my colleague caves and quits, I will also quit and let the entire organization crumble - is there any way I can take advantage of this?