There is a response to this, one which appeals to the transcendence of God. Certainly God, if he is utterly unlike anything in the created order just as the classical theologians tell us, to some extent will be beyond our intuitive notions of what goodness entails. How can a person claim to know a priori what God would or wouldn't do? This is also implicit in the "skeptical theist" response to the problem of evil: the mere fact that we cannot see that God would have some reason to do X by itself does not entail that there couldn't be any such reason; perhaps the reason is not the sort of thing we could figure out on our own.
The problem with this line of response, by my reckoning, is that it stretches the meaning of "goodness" beyond what I can accept as reasonable. If God allows various evils for the sake of our good, i.e. for the sake of promoting my welfare, even though I can't see the reason for which he might permit these specific ones or any evil in general to that end, that is all well and good. It is another thing altogether to call it "goodness" when God acts out of something resembling malice -- viz., knowingly predestining a person to sin and consequently to perdition. As I claim in my JAT article, God's goodness is his disposition to act for the benefit of the other person, especially when the latter is undeserving. When the object of the action is not the promotion of another's well being, then it is no longer good. I support this by appeal to various theologians as well as to a number of passages from the Bible:
Ps 23.6 connects God’s goodness with his mercy: “Surely goodness and mercy shall follow me all the days of my life.” At Ps 25.7, the psalmist begs God: “Do not remember the sins of my youth or my transgressions; according to your steadfast love remember me, for your goodness’ sake, O Lord.” This supplication is meaningless if God’s goodness does not dispose him to go beyond obligation and to treat the sinner with mercy; otherwise it would be perfectly compatible with God’s goodness if he were to remember the psalmist’s sins of his youth and his transgressions. So the following verse affirms: “Good and upright is the Lord; therefore he instructs sinners in the way” (v. 8), so that they might not suffer deserved punishment for their wickedness. At Ps 69.16, we find the following prayer: “Answer me, O Lord, for your steadfast love is good; according to your abundant mercy, turn to me.” At Ps 86.5, we find a further connection between God’s goodness and forgiveness: “For you, O Lord, are good and forgiving, abounding in steadfast love to all who call on you.” Ps 106 opens with the refrain: “Praise the Lord! O give thanks to the Lord, for he is good; for his steadfast love endures forever.” Goodness is paralleled with grace at Ps 135.3: “Praise the Lord, for the Lord is good; sing to his name, for he is gracious.” As Wesley appreciated (Walls 1992, 84), Ps 145.8-9 connects God’s goodness with his grace, mercy, slowness to anger, abundant steadfast love, and universal compassion. And a final, obvious example can be drawn from the New Testament: Paul writes to Titus that “when the goodness and loving kindness of God our Savior appeared, he saved us” (Tit 3.4-5). (pp. 68-9).
In all those examples, then, I argue that it is clear what God's goodness means: it means his disposition to act for the benefit of the other person, especially when this is undeserved. This is demonstrated also through its close connection with mercy and grace and salvation. But I also want to consider the following example from the Gospel according to Luke:
"Is there anyone among you who, if your child asks for a fish, will give a snake instead of a fish? Or if the child asks for an egg, will give a scorpion? If you then, who are evil, know how to give good gifts to your children, how much more will the heavenly Father give the Holy Spirit to those who ask him!" (Luke 11.11-13)
Notice that the persons who will receive the Holy Spirit are "you who are evil." Though these persons are evil, they nevertheless understand what goodness towards children means.They have some understanding of what it means to be a good parent. And at the same time, God will give these persons the Holy Spirit, despite the fact that they are evil, if they ask him. Once more, it seems to me that there is an implicit attribution of "goodness" to God in this context, and here goodness evidently means the disposition and willingness to do what benefits the other person, especially when she is undeserving.
Importantly, too, this is supposed to be something that Jesus' audience already knows. It's supposed to be something they already understand about God: that if they, being evil, are already disposed to give good gifts to their children, how much more is God supposed to be willing to give the Spirit to those who ask him? There is an implicit recognition that our understanding of what goodness means can apply in some way to God, although he certainly exceeds it in a good direction.
For that reason, when someone reasons that God could not predestine a person to sin and then damnation because not even a good person would do that, the reasoning is legitimate. God might well use other means for pursuing our welfare than we might have done -- e.g., permitting calamities to befall us so that we turn our attention to the Lord and away from the things of this world, as Catherine of Siena argues -- but as soon as he no longer is concerned for our salvation, then he is no longer acting out of goodness.