I am not an expert, but my neurologist and everything I have read would seem to indicate that you are unlikely to damage or hurt the nerves in any way through sensible exercise. What Kitt is talking about is the impossibility of regenerating dead or wasted nerve and muscle tissue due to CMT through exercise or any treatment, supplements, etc. in this case overdoing it can be damaging because it leads to fatigue and weakness and energy must be conserved, not squandered.
That doesn't mean that exercise isn't helpful at all in CMT cases. I am able to hike with poles on relatively level ground for several miles at a time. In this way I am able to preserve and even strengthen what muscle is still present and functional. In spite of this regime I am able to cover noticeably less ground than this time last year and the same route takes a little longer. I am tireder, my feet and ankles are thinner, the muscles are not coming back. Exercise does help with circulation and mental health, so even if one should not expect too much from it, movement should be deliberately incorporated in a daily wellness regime.

I cannot imagine being able to walk on a treadmill. My balance and coordination have always made it impossible. I fall down no matter how the doctor tries to adjust it for me.