CF is electrically conductive and as such acts the same a piece of wire.

Try it, use a bulb a battery and a piece of CF.

Any piece of wire running parallel to another will pickup the signal of the other, this can be rx output to the servo's or motor noise from pumps etc. It also acts a sort of 'faraday cage' (not a true one i know) but the effect is similar so signal strength is reduced when it passes through it.

It may be that in ideal conditions with a very strong tx signal the system will work satisfactorily but when other thing conspire against you (low level, far away other txs on adjacent frequencies, external spurious noise etc.) the weaker signal causes a lockout.

I have had very bad experiences with CF causing loss of range and would NEVER use an Ariel inside a CF fuselage.

Just recently a well known model builder in the UK who builds perfect scale models decided not to put an external Ariel (he had always done so before) he range tested and all seemed well. Many flights later out of the blue he had a lock out that cost the model.
There is no definite evidence that it was caused by the internal Ariel but the replacement model (same type) has an external Ariel and has had no problem (same radio).

In the early days of turbines in Europe Ariel were put inside the fuselage (as per DF) but many planes crashed (all with lock outs) since we all (or most) went to whip Ariel’s the problem has all but gone away.

In my opinion there is enough doubt to be cautious with you expensive jet and anything you can get in your favour you should do.

Paul