Sproul's discussion actually affirms a double predestination, and it doesn't escape the monstrous notion of my accusation because his escape is saying that God is not actively willing the sin.
My accusation rests entirely upon the fact that according to Calvinists the only thing separating the damned from the saved is the choice. Sin is a non-issue. It doesn't matter, so long as God chooses someone they are saved. No matter how sinful they act or how terrible they are. So what does it matter if God wills them to sin or not when sin doesn't even enter the equation of salvation, only God's choice? For double predestination God must will the particular damnation of individuals purely based on His own capriciousness.
It is that aspect that robs God of His justice and makes the doctrine monstrous, not as if God forces some to sin. Because again, sin is a non-issue in God's sovereign choice.