I agree the Igros Moshe seems clear that it’s a shas hadchak. The quote of Reb Dovid’s position came from Rabbi Frankel of the Aguda of 5 towns. The wife of one of my frieds is from the Lower East Side, and personally poured chalav stam for Reb Dovid. Every so often it pays to take an F train to the first stop in Manhattan, East Broadway, and speak to him yourself. I once did that and asked him. I spoke to someone else who told me that “shas hadchak” refers to putting frum companies out of business. It could be Reb Dovid is arguing on his father, but when I asked him he said that’s what the teshuva meant or something like that. Being that it shtims with what Rabbi Frankel said, I’m willing to accept it. But there is no argument that the pashut pshat reading of Reb Moshe ZT”L is like Big One.
As for the air conditioner timers, my rav and poseik said that we should only use timers for lights and air conditioners. I have to double check, but I believe that air conditioners are allowed because of extreme discomfort, and light are different for another reason which I forget offhand. Otherwise, we listen to Reb Moshe ZT”L. I will try to find out more exactly why these 2.
Rav Shachter doesn’t publicize his views on this because “tov sheyihyu shogegin” and others argue on him anyway, but he says that nowadays, most dairy cows are treif, even without the “displaced abomasum” cows, and when all the milk is mixed togather, there is no biltul berov, and definitely not bitul beshishim. Rabbi Belsky argues, and on this basis I drink milk. As for why today’s cows are worse than they were historically, it’s only in the last 100 years or so that people bred specialty cows. It used to be that cows needed to be hardy or they wouldn’t survive. Today we breed cows for soft meat (Angus, Kobe, etc) or for dairy production (Holstein etc). Furthermore, today’s cows are in stressful environments to make mass production possible. The zebu cows are much hardier than our European cows. their meat is also like shoe leather, which is why chicken and geese used to rank higher than cow meat on the “chashivus” totem pole.