They are hated
1) Because they are the most proliferous writers on the subject of EENS as it is written, and since "by the end of the decade following
the Second World War—most North American Catholics had ceased to believe
that their good Protestant and Jєωιѕн neighbors were going to eternal ruin at
death, invincibly ignorant or not", 99% of American Catholics find the traditional teaching of EENS abhorrent. They say "This is a hard saying; who can hear it? They can't stand hearing it. They therefore can't stand the Dimond's writings.
John 6:60-68- “Many therefore of his disciples, when they had heard this, said, This is a hard saying; who can hear it? When Jesus knew in himself that his disciples murmured at it, he said unto them, Doth this offend you?... From that time many of his disciples went back, and walked no more with him. Then said Jesus unto the twelve, Will ye also go away? Then Simon Peter answered him, Lord, to whom shall we go? Thou hast the words of eternal life.”
2) They are steadfast sedevacantes. They will attack anyone who disagrees, just like all sedevacantes do. If sedevacantes didn't believe in what they teach, they would not be so adamant. The shepherd is struck (Pope), the sheep are scattered. Maybe the sedes are right, on the other hand maybe they are wrong.
Combine 1 and 2 and you have a unique situation. There are very few people who are sedevacantes and also adherents EENS as it is written. That is why they are so hated.