Yes, “defuse” would have been the correct word to use in this context of dismantling or disabling a bomb.... “diffuse” does not make sense in the context of removing wires or separating bomb components, unless the English have such a use of the word that is unfamiliar to me.........
from dictionary.com
diffuse:
–verb (used with object)
1. to pour out and spread, as a fluid.
2. to spread or scatter widely or thinly; disseminate.
3. Physics. to spread by diffusion.
–verb (used without object)
4. to spread.
5. Physics. to intermingle by diffusion.
–adjective
6. characterized by great length or discursiveness in speech or writing; wordy.
7. widely spread or scattered; dispersed.
8. Botany. widely or loosely spreading.
9. Optics. (of reflected light) scattered, as from a rough surface (opposed to specular).
It is nice to know there are still people in this world willing to risk it all for their fellow citizens!