That's not what he's referring to, though. In chemistry, bonds between "atoms" are ordinary chemical bonds, held together through electromagnetic forces, and yielding typical chemical reactions like explosions and deflagrations. Fission and fusion are "nuclear" processes, operating between protons and neutrons within the nucleus of an atom only, and moderated by the strong nuclear force. The energy released by breaking these bonds is orders of magnitude greater, and what we normally refer to as a "nuclear" explosion. Calling it "nuclear" vs. "atomic" conveys useful information about what's actually going on when it detonates.