Solomon shows that he is wise. He has knowledge and understanding of God’s law. God’s law says that the altar offers no protection for murderers who had deliberately killed someone (see Exodus 21:14). So the altar offered no protection to Joab who murdered Abner and Amasa.
29 And when it was told King Solomon, “Joab has fled to the tent of the LORD, and behold, he is beside the altar,” Solomon sent Benaiah the son of Jehoiada, saying, “Go, strike him down.”