A couple of thoughts:

1. Killing senior leadership is a slow road to victory (Except in a case where some guy with legal power over people is forcing them to do things against their will. UBL's power is the power of the conditions he exploits, the power of his cause, and his supporters are all volunteers.) Killing him will not weaken the cause, but could make it stronger.

2. Capturing him and attempting a civilian trial under US, or even international, standards would be an IO disaster for the west.

3. He will be replaced. Take out UBL, and AQ gains a new leader who may actually be more effective than the current one. Take out AQ and a new organization will form that may well be more effective than AQ. Success lies in addressing the causes, and so long as the majority of senior leaders believe it is a mix of "malign actors" and "radical Islam" we will continue to chase our tails on this. (both of those are necessary aspects of how the causation is exploited, but are not causal in of themselves).

4. Should we kill him? Definitely. Quietly, relentlessly pursue him and his core followers to the corners of the earth and terminate them where we find them. They have earned that. But that is a handful of guys, and should not be confused with the nationalist insurgents across the globe that respond to the UW efforts of AQ. But as to the causation they exploit, as to the conditions of insurgency in so many countries that they exploit, as to the sympathetic supporters in western communities that either empathize with the people in oppressed lands, or feel strongly that their government at home is an oppressor (or at least an enabler of oppressors); that will all still be in place, and that is the real problem that must be addressed, and killing UBL will have no positive effect on that. That will require an evolution of US foreign policy and will also require evolution of many domestic policies in the nations where this causation is the stongest as well.