Brother Edmund Garvey was awarded the honour in 1997.
Since then, he has overseen a controversial legal strategy, which requires survivors of child sexual abuse by a Christian Brother, who want to take civil action against their abuser, to sue each member of the religious order which has over 100 members.
In an email to councillors last month, Paul Murphy described Brother Garvey as a "blameless person" and said "there is a danger that the issue will become personalised on one individual." He has since resigned as chairperson of the support group.
In a statement issued on Monday, Dignity 4 Patients CEO Adrienne Reilly said the letter in no way represents the views of victims, the Board, or the group's staff.