Powdered milk may be a different shaila than cholov stam.
Who could believe hearsay that their mothers brothers bubbas husband personally witnessed Hershy bars in Reb Moshe’s fridge or their best friends wife’s mother personally poured cholov stam milk in Reb Dovid’s mouth? You either have a mekor or you don’t.
There is no “interpretations”. Reb Moshe twice wrote bshas hadchak, and Reb Moshe meant what he wrote.