All 4 were disfellowshipped for believing that the entirety of the ransom, including the new covenant, and the mediatorship and everything else in the bible, applied to everyone. I can tell you that none of them wanted to be disfellowshipped, but there was no choice really.
And there it is, simple.
As for the courage - I really don't think it was that as such. Really, they asked, and kept the inquistion up aginst all of us, interviewing all our friends and associates, monitoring us etc, for a period of months (they recorded one of my public talks and made constant reference to it in my JC - i have it somewhere, will try to dig it out) - what can you do? Deny what you know to be true just so you can talk to your friends and family? I know others have made that choice, and that is absolutely fine and right for them, because of their circumstances - but for me and the others at the time......well, it just got to the point where you have to decide - lie and deny your beliefs, or just tell the truth. I suppose we just did what we had to. There was no courage, believe me!
Matthew 19:29 (New International Version)
29 And everyone who has left houses or brothers or sisters or father or mother or children or fields for my sake will receive a hundred times as much and will inherit eternal life.
Welcome to life, it starts right away :)