Catch yourself: a couple of corrections.
The Chazon Ish was mattir milk (although not in the C.I., it has been writted that he was only mattir for children when there was no other milk) based on the Pri Chodosh, which is not the same as R’ Moshe’s heter, which applies despite the fact, R’ Moshe writes, that the Pri Chodosh’ heter was not accepted.
The heter for butter is a different heter.
R’ Moshe himself writes that keilim should be kashered, although R’ Yaakov Kamenetzky in Emes L’Yaakov disagrees.