While Corbyn might have a bit of a point I don't agree that Bin Laden's death was a "tragedy" -- far too strong a word in the circumstances. Regrettable, perhaps. Even those who dismiss the idea of holding a trial would probably (hopefully) admit that, in theory at least, a trial would have been preferable. It's just that valid points such as practical concerns over expense, security considerations, etc etc aren't so easily dismissed, and holding a trial would have been practically very difficult indeed. Since just about every country in the West would want to charge him anyway, I could well imagine extradition claims dragging things out for years and years.
On the other hand, killing him hasn't achieved much either. Al-Qaeda and the Taliban function effectively without him. ISIS are a separate group anyway. And the damage he had done had long since already happened. It's some very little justice for his victims, though, and the world will certainly not miss him.