I agree with Steve about removing the cover from the compression post inside the boat and having a look. It is the door jamb to the head. If you look closely there are wood plugs that cover the screw heads. Remove the door from the hinges and those screws. That piece will come off and you can see the actual compression post inside the teak cladding and even peek up in the wire chase to look for compression or rot. In regards to the method used to measure moisture content, the instrument could be fooled in that area. Firstly, there is a large plate of aluminium under the fiberglass at the mast step. If this meter is based on a capacitance measurement, then it may be a false interpretation of the results. The only wood is pretty far removed from the deck. There is the top layer of glass, a 1/4" plate of aluminum, then 3/4" of a synthetic core material probably not effected by moisture, another layer of glass and finally the wood block inside the overhead beam. Since the wood is only separated by one layer of fiberglass inside the boat (the thickness of the bottom of the beam) I would suggest taking the moisture measurement from there if physical inspection is not possible. Look for other clues like the beam being distorted as if the wood inside was compressing. Do the doors all close easily? Is there any evidence of the silicone sealant at the top of the bulkheads tearing loose? And finally, is the rigging excessively loose? Perhaps if none of these secondary conditions exist, it is a good structure. The repair is pretty straight forward and has been performed by many a DIYer on the site.
Regards,
Allan