Yitayningwut,
I meant to post this rebuttal after Pesach but I forgot.
I don’t think your argument that my pshat is not “pashut pshat” holds up in this case. You say that given that the Gemara is listing things that are Erva it is cannot be pashut pshat that “erva” means different things regarding each one. If this were the Rambam or the Shulchan Aruch, I would agree with you. However in two respects the Gemara here is different:
(1) Gemara is not meant for laymen to be able to just pick up and read, it is meant (like mishnayos) to be learned with a Rebbi who will transmit a mesorah as to how it should be understood (in this case Rashi.)
(2) More importantly, this is not one person giving a list. These are statements of Amoraim who lived hundreds of years apart. Therefore the inference that they all meant the same thing by the word “erva” is not nearly as strong.
Finally, you wrote: “Shir Hashirim is a much better place to bring an asmachta from, because it is all about hirhurim. Since hair and voice are mentioned in Shir Hashirim, we don’t need to run to other places. The shok of a woman is not mentioned in Shir HaShirim, therefore we have to resort to an obscure siman l’davar.”
There are two problems with this:
(1) There are other body parts mentioned as a source of tayva in Shir Hashirim that were almost certainly covered in the times of Chazal, but are not mentioned in the Gemara.
(2) While the word “shok” is not mentioned in Shir HaShirim, the other word for the same body part, “yerech” is mentioned: ???-?????? ?????????? ????????????, ????-??????; ????????? ??????????–?????? ????????, ???????? ????? ??????.