To actually address the question of the thread topic… 
No, I don’t think Rob would have had a difficult time explaining Bin Laden–he is well aware of the existence of super-sinners in his book.
I also think, however, he took the rhetorically easy way out in his promotional use of Ghandi, and I wish he had been more courageous to take the harder road in promoting what he was talking about.
(Any example he borrowed would fall apart under scrutiny of course; Rob is well aware we’re all sinners who have fallen short of the glory of God, and he never once indicates he thinks people get into heaven by being ‘good enough’ in some way. He undoubtedly chose Ghandi because like Mother Teresa Ghandi is a popular and well-known example of ‘a good man’ in the public perception, but unlike MT Ghandi was not a Christian. Since his case doesn’t rest on Ghandi’s supposed moral perfection, pointing out realistic moral flaws in Ghandi doesn’t obviate his point.)
As other people in the thread have pointed out, your challenge implies that few if any people would think it “good news” that Bin Ladin could have been saved from his sins before he died and so be in heaven with them eventually! If they have problems with Bin Ladin being led to repentance and faith in Christ after death, simply on the ground that a “bad man” like him shouldn’t be in heaven by the grace and salvation of Christ, then by the same principle they would have had problems if he had repented and converted before he died, too. Even if they didn’t want to (or dared to) express it.
At the end of the day, the people hired first complained about the people hired last being paid the same wage by the generous master. “Is it not Mine to do with as I please?–or is your eye evil because I am generous?!” That’s a warning to the ones complaining about those being called last getting in anyway: and the same principle would apply if the master in the parable had called the remaining people in to pay them after the day of labor had ended, too! Because salvation is not earned by works, but is freely provided by the grace of God. (Of course that parable totally focuses on the calling of Christ–to all the people in the courtyard eventually, by the way!–and not on repentance of sin, as other sayings focus on, sometimes to the exclusion of any action by God at all. But neither concept should be ignored.)
Anyway, my emotional churlishness that an enemy of mine might be led to repentance and saved from their sinning by Christ and brought into the kingdom, whether sooner or later as the case may be, doesn’t keep that salvation from being good news!–thank God!
It might however keep me out of the kingdom until I repent of my churlishness against the salvation of Christ’s enemies by Christ. If I deny that Christ’s enemies can or should be saved, then how can I the sinner be saved?! If I deny the name of “Jesus”, “the Lord saves”, then how can I be saved!? The older brother is about to be in big trouble with his father if he doesn’t improve his attitude about his younger brother who might as well have been dead and destroyed in hell–but now is alive and found! “You… wicked… SLAVE! I forgave you all that debt because you begged me to! Was it not required of you therefore to have mercy as well on others!?” Imprisonment and torment of the forgiven slave follows…
(For however long, until he should pay up the final farthing he owes. Which is not the embezzlement he was forgiven of… What does the unforgiving slave really owe? “Thus shall your Father in the heavens be doing to you, each one of you, unless–”?)
So true! I suspect we over-value *niceness. *