using the same pronoun twice in the same sentence?
Let's simplify the sentence so that you can see that both "Mr Trump" and "he" must be there:
[Mr Trump will never forgive those](A) [whom (...) he judges to have failed him](B).
You have (A), the main clause whose subject is Mr Trump and then you have (B), the relative clause modifying the pronoun those, whose subject is he.
You cannot say "I know those whom love", a subordinate clause needs a subject. You need to say: "I know those whom I love".