In the Ultimate Marvel Universe, Thor (Thorleif Golmen) is a fictional superhero based on the Marvel Universe version of Thor. Thor is the Asgardian God of Thunder based on the deity of the same name of Norse mythology and a founding member of the Ultimates.
Thor is the opposite of non fictional 
The opposite of non fictional is fictional, making this correct. I think the model got confused because it doesnt know what non fiction is.
( z1 opposite :ARG1 ( z2 person :name ( z3 name :op "Thor" ) ) :ARG2 ( z4 person :mod ( z5 fictional :polarity - ) ) )