I was endeavoring to translate the following sentence from Asimov's, I, Robot:
He cast one glance over his shoulder at the blackness of the cliff’s shadow and realized that he had come too far to return — either by himself or by the help of his antique robot.
with:
Er warf einen Blick über die Schulter auf die Dunkelheit des Schattens des Felsens zu und begriff, dass er zu weit hergekommen war, um zurückgehen zu können -- entweder alleine oder mithilfe seines antiken Roboters.
However, 2 native German speakers corrected me with:
Er warf einen Blick über die Schulter auf die Dunkelheit des Schattens des Felsens zu und begriff, dass er zu weit hergekommen war, um zurückgehen zu können -- weder alleine noch mithilfe seines antiken Roboters.
Ignoring, if you can, all other errors that may be present in this translation, my question is, do you agree with their correction and, if so, why? Specifically, beyond personal preferences and subjective interpretations, is there any German grammar that compels one to choose one or the other of the words? Personally, I do not see how there could be any confusion regarding the meaning, in this case, and "entweder" matches the English "either", whereas "weder" does not.