I would say that if he didn’t ask anyone’s opinion about it; then it’s no ones business except his and God’s.
AMEN
Why question why any man would want to be baptized again?
Many Christians, for personal reasons are baptized a second time and maybe more.
I was baptized when I was 11 yrs. old. At age 55, I was baptized again. You will feel renewed, that was the best feeling.
It all depends on your relationship with God, only you would know. Naysayers should remain quite!