Seriously? At least own up to it. Why did you ask if he wishes he kept his son away from his sister? Why do you ask questions indicating that there is no hope of him becoming a grandfather? He'll cement his orientation? Men are never 'welcomed back'? Accept him for what he'll become and end the nonsensical pursuit of his acquiring straight labels?
There isn't much of a gray area. If you're going to try to insult someone by using his child as ammo, at least be honest about your intent.