Paul persecuted and killed Christian’s. I don’t know this man and neither do you. The pastor says his life has been transformed. That’s not for me to decide. The pastor is aware of his background. Considering what some do who are “wholly santified” I’ll take the pastors word for it
BTW, God is in the business of forgiving sinners. Just recollect the man in Corinth who was having sex with his father's wife. But I am convinced Paul would not have recommended that man for leadership if he repented and began the straight and narrow.