Purely your opinion and I'd welcome an example of a view from someone besides yourself who thinks it doesn't imply 100% fibre, I've yet to see one.
EDIT: Even Virgin admitted it implied as such and justified the ad based on the active nature of the network and the quality of the coaxial component. The fibre optic claim was based around the network being amplified and resilient to interference, that it implied the network was entirely fibre optic was not contested.