This may be true for an individual who willfully wanted it and dedicated his/her soul to Baptism, but there are those who were led to the alter and baptised who did not believe in it's sanctity. Like parents who have their child baptized and the child did not willfully ask it to be done, based on his/her commitment to Christ.
Which means they were never saved in the first place. This young man need not denounce his baptism since it never occurred in the first place in the eyes of God. This young soul will die with the beast in the field, by his own free will.
It’s not an analogy, so the rest of your discussion is moot.