Belitt for a while (in the sixties) had the only widely available translations of Neruda in book form, the only version of Poeta en Nueva York in print. He was the "leading translator." So the resentment about the quality had to do, possibly, with the fact that the American reader with no Spanish had to go through Belitt to get certain things. To then interpose his own poetic personality in such a case seems an affront, given that a reader may or may not want to have to deal with the "translator's ego" (phrase from Weinberger & Eshleman.) It's making a claim on the reader's attention that would only be justifiable --maybe--if BB were a great poet "in his own right."