Who is Simon Goldberg from Extremely Loud and Incredibly Close and what is their importance?

Introduced to Thomas Schell, Sr. (Grandpa) while he is anxious to find Anna Schmidt, Goldberg is introduced by her father as "one of the great minds of our age," while he claims to be simply "trying to be." He is curly-haired and disheveled, with charcoal handprints on his white shirt. Herr Schmidt grants Goldberg asylum for as long as he needs. Goldberg declares angrily that humans will kill humans until there is no one left to fight. Later Thomas learns Goldberg is interred in a Nazi labor camp.