Solomon's words to Abiathar, and his silence, imply that some recent conspiracies had been entered into. Those that show kindness to God's people shall have it remembered to their advantage. For this reason Solomon spares Abiathar's life, but dismisses him from his offices.
In case of such sins as the blood of beasts would atone for, the altar was a refuge, but not in Joab's case. Solomon looks upward to God as the Author of peace, and forward to eternity as the perfection of it.
The Lord of peace himself gives us that peace which is everlasting.