Your argument does not make any sense.
The priest, regardless of his vows, still has free will to choose to commit a sexual sin.
A non-vulnerable adult to whom the priest makes a sexual advance also has free will to agree and choose to commit a sexual sin with a priest.
The priest breaking his vow of celibacy does not make him automatically guilty of “sexually harassing” a consenting adult.
So the bottom line is, should a priest be automatically laicized for breaking his vow of celibacy with a consenting adult. I would say it depends on the priest and the situation, and that the priest’s superiors are in the best position to decide what to do for an individual priest.