Sam appears to be a worshipper of Saradomin,[1] and has thusly (mis)interpreted the teachings of Saradomin to hating monsters and the ideal that humans are his chosen race and all other races exist only for servitude.[2]
Sam met his end during the assault launched on Sigmund's base under ambiguous circumstances, as it is unknown if goblin soldiers or the ensuing cave-in killed him.
^H.A.M. agent Sam, "The Chosen Commander", RuneScape. "Saradomin hates monsters, so I do as well. Humans are Saradomin's chosen people; all other races are fit only to be our slaves."