When people repent and then commit by following through as God directs, how well do they already know their own heart? When we are very young we may believe we know about everything. I recall at the age of 12 thinking I was already smarter/wiser than my parents and all of the adults around me. Of course, I was wrong, but it was not until I really was walking with God that I gained enough wisdom to realize how little I really understood. Now at 76 my greatest understanding is the realization of how little I still understand, not so much about people anymore, but about God. A lot of people, even on this forum, who act as if they had all of the answers about God. I really doubt that.
What is an unrepentant sinner doing in the water of baptism? God provided through the sacrifice of Jesus and the outpouring of the Holy Ghost everything a man would need. But man often riding too close to, or even on, a lukewarm fence looks where he should not and seeing something he wants rather than needs goes for it. Therein often lays the problem of followers of Jesus. They take their eyes off Him and lay them on something else for too long a period of time.
So then maybe it is not that he was unrepentant for likely most people in that situation in the water really are... at least of the many things that might come to their mind, but were any of their doors unconsidered closed to God, or did any of their doors get closed later when they gave a second thought?
I was not expecting from you a startling revelation, but just some considering perhaps similar or better than what I have done.
On the other question I asked about David, how many of us go to face our giants "in the name of the Lord of Hosts" or as we might say, in Jesus name? I might be able to answer it already but I keep on seeking and God does keep on providing more.
We know or believe now that anyone can come to God with repentant heart and receive the gift of the Holy Ghost. In the OT I would say that most people could not do that. They had to go through the sons of Aaron [priests] or to one of God's prophets in order to receive God's direction. Where would you say that puts David, the shepherd boy, who slew Goliath?