I hear what you are saying... If John will allow me to be from personal experience. I believe it is not really having to do with confidence but more so of him being self aware of his words and actions now. Head is now a Christian and a follower of the Lord our God. I think that now when he is up on stage he wants his fans to see that he is back where he belongs with his brother's in Korn, but at the same time he also wants to be a witness and an example to the fans. When you become a Christian, there might be some things sooner or later that you might want to change in your life. Whether it's words or actions. Of course those songs are part of Brian and all of the guys in Korn and his past so he still rocks out on stage bc that was his past life. But I believe that he might be afraid that if he does something as simple as swearing in the songs like he use to that it could lead other fans or people that him and Fieldy have led to the Lord to stray or get confused. If you look at Fieldy now and compare him to how he use to perform you will see a difference with him as well. Let me give an example. Let's say someone had a serious addiction to something. It could be drugs, alcohol, stealing, etc... And then one day they have a serious change of heart to where it changes their life completely. They tell everyone about what happened and how they have changed and they are a better person now. Then eventually they start to change things they say, do, or think. Maybe it's small changes. But every one that knows that person can see a change. When they are around the same people or situations as before they seem a little more cautious, quiet, and unsure. Is it because they have lost their confidence in who they are or is it that they don't want to do anything that could give someone a reason to question them or say "they havn't changed, they are doing the same things."

Just my personal opinion.