I wonder about a couple of the details of this antenna, first why are
the reflector elements insulated from the boom?

1) In the Ham world, if the element goes through the boom and is
electrically in contact (shorted) the width of that boom is subtracted from
the total element length when calculating resonance, directors and
reflectors.

2) It may have rotating elements to accommodate shipping and installation.

Those are my guesses.

PP