heretofore-
I’m sorry I was unclear, let me clarify: I did not hear specifically from R’ Moshe’s sons that it is assur to be machmir. What they did say was to the effect of “there is no reason for you (not me personally, you as in stam a person) to be machmir” and “don’t worry about it, there’s absolutely nothing wrong with it.” And they were speaking to choshuve bnei Torah who learn full-time in yeshiva. And I know firsthand that R’ Dovid consumes chalav stam on a regular basis, and when a friend of mine asked (with a bit of chutzpah) “Isn’t the Rosh Yeshiva a ba’al nefesh his father spoke of?” He replied half seriously “It’s not your business.” From my impression of his responses it seems to me that he is against being machmir in this area, but that is only my conjecture. However my personal rav, Harav Yitzchak Abadi, does happen to hold that way.
The story in the Gemara was not about the Zohar. The person was wearing black shoes as a sign of Aveilus for Yerushalayim, something he was not halachically required to do. Yes, there are 70 faces to Torah, but that is for expounding and drush, not for pshat, and I think the pshat is clearly indicative of my point, that in matters of issur v’heter one should not do more than what the halacha requires if he is not holding there.
I am not saying that you have to accept c.s. as l’chatchila or mutar gamur etc. On the contrary, if your rav disagrees you should follow him. I am just trying to inform you that there are those who disagree, and they are great people too, so you shouldn’t be dismayed when you see people being noheig differently than you.