I guess it depends on what you mean by "value".  There is no question that
the specimen has the greatest scientific value in its present state.  But, a
club auction has to also be concerned with monetary value, and I'm pretty
sure the bidding would be more competitive on a well cleaned specimen than a
fresh frozen one.  Also, if you plan on selling it as a specimen shell,
there is another good reason to thaw and clean it, much as I hate to mention
it - to make sure the shell didn't crack during freezing, or from a
subsequent impact.
Paul M.