Two things:
1) apushatayid- You are simply mistaken. Without Reb Msshe zt”l’s heter, there are only two type of milk; Cholov Yisroel which is kosher, and Cholov Akum which is not. Reb Moshe is the one who classified the milk of the companies as Cholov Stam, not Cholov Akum, and permitted the milk, albeit not as a l’chatchila.
2) It is important to note, that the heter of butter no longer applies. Although many poskim permitted butter because it can only be made with cows milk, nowadays their are dairy additives which are added to the butter. Those additives/ingredients are Cholov Yisroel sensitive, and therefore for those who are makpid on Cholov Yisroel, there is no heter to eat Cholov Stam butter.