Hebrews 13:4 is not dealing with who can be leaders and who cannot. It is simply a call for marital purity in the body of Christ along with the avoidance of monetary greed. Further, it is stating that those who ignore the call to moral purity will experience the discipline of God, which certainly includes certain moral consequences, but does this mean they can never experience God’s forgiveness and restoration to usefulness? Of course not. Compare Peter after his denial of Christ and David’s sin with Bathsheba. The author doesn’t discuss all the issues, but is simply giving a general admonition and warning and this must be understood in the light of the whole of Scripture.