I would think that was how it was, also.
I have a hard time believing that Charles Finney actually quit his ministry solely over the fact that
Fr. Nash died. On the other hand, I can easily believe he quit his ministry when God showed him it was time to quit.
But apparently his relationship with Fr. Nash was an important one. And I think that may have been the point the writer of the article was trying to make, as the writer writes much about the ministry of intercession.
(You probably know all this, but, for the benefit of others who may not ... )
We all pray, and then there are those who are actually called to intercession as a ministry.
I don't know how often this occurs, but probably much more often than we know as much intercession is generally done 'hidden' from the public eye.
When one is an intercessor, the Holy Spirit will sometimes impress upon the intercessor's heart to pray for a certain person, ministry, event, etc. It is like God "assigns" an intercessor, in a very committed way, to a particular task, for a specific period of time. Sometimes for a lifetime. I suspect Fr. Nash felt committed to pray for Finney, and Finney was aware of this.
I saw these dynamics in action when I worked in the Assemblies. There was a woman committed to interceding for the church there. She did lead others in time of prayer but was firmly committed herself to continually pray for the needs of that church. She was always available to the pastoral staff for prayer requests; she worked closely with them in her prayer ministry to the Body of Christ there. She was a blessing to that church, and perhaps still is.
I recently read a book where the author began it by "thanking' those who had helped him in the writing of the book. He did not fail to mention a woman who had been an intercessor for him throughout most of his ministry. Apparently, God had put that assignment on her heart, permanently.
How often does this happen? I'm told it was known to happen often in the past. But I suspect it happens much now, too ...