Jothar, The Gedolim supported Reb Amram and the NK. Rav Amram was the NK, and the NK was Rav Amram. So you can’t differentiate. Specifically both the Chazon Ish and the Brisker Rav were close to Reb Amram and supported his, and the NK’s, activities, as the article in this week’s Hamodia by Rav Yishai Sofer explains. (See the extended article in the paper. The other thread are just excerpts.) I haven’t seen the book by Mr. Lorinz, but at most he could have been referring to a “lone ranger” who whilst a member of the NK, under no circumstances was his comment to the CI anything other than his own, and in no way represented the NK. As mentioned, the CI and The Rav supported the NK and Reb Amram.
(Of course we are talking of the original NK and the small kehila that is in Eretz Yisroel. Not the clowns parading around under that usurped name.)