Li Chen eliminated Li Gui with a single stroke, a move that could be interpreted on two levels.
Being the scapegoat for the Chen Family, it was Li Gui who swaggered and deceived, having no ties with your Chen Family. Now that I have killed him, there's no witness left to tell the tale.
Of course, the notoriously feared Immortal Master Li is no benevolent layman; he certainly wouldn't repay evil with good, or engage in acts of kindness without reason.
Rumors have always circulated that he is a Killing God, someone who slaughters whole cities and exterminates clans just to vent his anger. Although this might be an exaggeration, the number of Dead Souls that have perished by his hand already tallies up to ten thousand. A hundred or so more would hardly make a difference.
Not to look too far, the current case of Li Gui is the best evidence of this.
Now that Li Chen has set his terms, if the Chen Family remains obstinate, then Li Gui serves as a grim premonition for them.