Jerry,
By identifying the presence of the insulation, evenly distributed, at a uniform depth of approximately 1"; and, recommending that a qualified insultion contractor examine the situation further, to determine whether additional insulation is appropriate, I have, in my opinion, properly advised the client as to a probable defect without attempting to ascertain the existing R rating.
Remember, the question was whether we needed to state an R factor for blown insulation, which I believe is beyond the scope of a proper inspection.
Gary