I could be wrong, but that's semantics my friend. To say a hormone is synthetic is to say it is not naturally occuring, artificial. If these "bioidentical hormones" are not naturally developed (such as by a gland) then they, too, are technically synthetic. It's a metaphysical distinction of necessary truth.
Unless it's actual biologically produced hormones, those Doc needs to check a dictionary. A quick read reveals that this "bioidentical hormone replacement therapy" involves synthetic hormones that differ from normal HRT hormones in that they are chemically identical to natural hormones, as opposed to those with different chemical structures.