Satan’s greatest weapon is God’s character?

I came across this otherworldly quote in the book, “Pierced for Our Transgressions” by Jeffery, Ovey and Sach. The quote itself is taken from Henri Blocher’s “Christus Victor”:

“But how is Satan’s role as the Accuser related to his power? If Satan’s opposition to the Lord were a matter of mere power, the rebel’s finite resources would equal zero confronted with infinity. But the Accuser can appeal to justice. [italics mine] He may also indulge in slander, but his force resides in the rightness of his accusation. Joshua is unclean, unspeakably unclean…(Zech. 3:4). The righteous Judge of all the earth, who can do only right, cannot refuse to hear the charges the Accuser brings without denying himself. In other words, the weapon in the devil’s hand is God’s own law, God’s holy and perfect law - “

Blocher is explaining how penal substitution is necessary for sins to be forgiven. Where he is going is the point that God’s justice, righteousness and holiness cannot be ignored during the process of reconciliation. Something had to be done. What was done was Christ’s substitutionary death on our behalf, exercising God’s love and satisfying His justice at the same time. What an incredible point!