Even flying directly into a dump stream would not cause much concern. Any fuel passing through the intake would be in small quantity and would pass through the burner section much like rain. Fuel is diffused almost immediately into vapor further reducing any impact on an aircraft flying through it.
I wouldn't give much thought to area traffic taking any risk from fuel being dumped by a distressed aircraft. Of more concern would be the nature of the emergency's effect on the aircraft maintaining its cleared flight path.