Graybeard,
Airbus adopted shunt antennas in the fin from the beginning. I don't know how well they understand the dynamics, but feeding hundreds of amps into a carbon fiber fin makes me wary. That said, I have no direct experience with A/B HF antennae. AA587 and prior events it highlighted really had me wondering.
I have a high respect to EMI/EMC and i am addicted to safety.
In this case i indeed donīt see problems:
1) The shunt feed "excites" the VS metal structure with the high current (at feed point) going to large section aluminum parts.
2) As far i know the "new materials" is not to (or cannot) "receive" RF current. The RF current will "prefer" to be circulating in metal sections. In an all plastic VS you can integrate a wire to "carry" the current.
3) I did not see a relation to the "hard input" to AA587 rudder to our discussion. RF could damage the new materials VS? They tested, for sure.
4) One dangerous issue is, like i commented before, EMI/EMC to yaw damper system like ChristiaanJ commented on Concord.
Obs. B787 was hit by a lightning bolt during a flight test. And survived.
The currents in this situations are much higher than the ones delivered by an HF transmitter even if the operator keeps it at maximum power with high noise in the microphone.
I will investigate this issue asap.