lesschumras: “LU, who are the Rebbaim that you are referring to? You make it sound like they are apart from MO but have a role in deciding if MO is Orthodox.”
I probably should have qualified the statement by putting “my impression is” in front of it. I didn’t do so because I thought it was a given although I don’t have sources. To answer your question, I do not remember who the Rabbanim were, but I read that many Rabbanim declared them as being non-Orthodox. I thought that both MO Rabbanim and Chareidi Rabbanim considered them non-Orthodox, unlike all other streams of MO which (as far as I know) have not been declared as non-Orthodox. I think it may have been the RCA which declared them as non-Orthodox. There are probably others here who know more about it.