However, what I'm not willing to suspend is that the Bat is capable of reaching the minimum safe distance of six miles off the coast of Gotham
A 4 MEGATON bomb wouldn't have a blast radius of 6 miles. "Little boy" was 15 KILOTONS and had a blast radius of 2 miles.
I'm thinking at least 30 miles blast radius and therefore Batman and Gotham would have been doomed.
Your facts are meaningless to me!
I'm basing the 6-mile radius solely on on-screen dialog. It was clearly not adequately researched. Of course, its just one of the many plotholes in the film.
How does Bruce Wayne, who doesn't even have shoes, get from an Asian desert all the way to Gotham, which has no bridges, without being seen?