Yes, politically we probably cannot justify killing him, at least not yet. But, I sometimes indulge myself in dreaming of a world purified of all scumbags, and perhaps let my youthful idealism take the better of my judgment in this case.
I dream of a civilized world, where it takes a whole lot more to justify killing someone than just having a criminal dad or unpopular ideas.
What's striking about this comment is that it seems to square with the senior Bin Laden's world view much, much more than the son you wish to have killed. This is probably how the terrorist bin laden sees the world: "Oh, if I could just kill everyone I need to, the world would be great....so I'll start at it by any and all means necessary."