If there is unburnt fuel I agree with this. However, I thought the point of a fuel air bomb was that you mixed the fuel in the stoichiometric ratio to get a huge explosion. By the time there is a pressure front, there should be no more fuel.
The way I visualize this is first you have fuel distributed in a sphere. The outer portion is too lean to react, the inner too rich, and the middle which reacts instantaneously to create your FAE. I’m having trouble imagining how the outer lean portion, when compressed, will react violently enough to add a significant pressure effect to the bomb. It would probably look cool and yellow though. I think it might slightly oppose the FAE part. Any idea how significant the unburnt fuel element of the bomb is?