Sforno on Numbers 25:13/ספורנו על במדבר כ״ה:י״ג

1תחת אשר קנא לאלוקיו, seeing he had had the courage to fight My fight, I have ennobled him, granting him “peace” [a fitting reward for a noble fight. Ed.]

2ויכפר על בני ישראל, seeing that he did what he did in full view of his peers so that they would obtain expiation for not having protested Zimri’s behaviour, he proved himself fit to become a priest whose primary function it is to secure expiation for the sins of their Jewish brethren. As a priest he could continue in the role he had first adopted on this occasion.