In the play, "The Crucible", what's the irony of Hale attempting to persuade Elizabeth that John should make a false confession?

Before Hale became disgusted with the large numbers of people who supposedly practiced witchcraft, Hale forced many other Salem residents to make a false confession. Now he is asking Elizabeth to convince John to falsely confess, not because Hale believes John is guilty but because he knows he is not. By confessing to trumped up charges of witchcraft, Proctor will save his own life. This might help ease Hale's conscience but it will ruin Proctor's reputation and his name. After talking with Elizabeth, John agrees to go along with the false confession until Danforth orders the confession nailed to the church door for all to see. Proctor realizes this will ruin his name, something he is unwilling to allow.