I still am looking for an explanation that prevents current flow thru
the center.

Well, being a logical person, I would ask what mechanism
of physics keeps the forward current from flowing through
the center to start with? Why doesn't the forward current
flow through the center and the reflected current flow
back on the surface?

Whatever that mechanism is, it seems logical to conclude
that it might also prevent reflected current from flowing
back through the center.

If we put a signal generator at each end of a wire,
which current flows on the outside and which flows on
the inside?
--
73, Cecil http://www.w5dxp.com