I believe this is yet another instance of a character being written as a mathematician precisely because of the stereotype that people who are interested in mathematics are not fully human. Just as Pi and Good Will Hunting are films which seem to be based on the false dichotomy between humanity and mathematics, this appears to be another one. I say "false", because 99.9% of the mathematicians I know are outgoing, kind, caring, friendly people very much unlike the monsters commonly portrayed in fiction...and I say "appears" because I have to admit I have not actually seen this film.

But, consider the following descriptions from people who have:

"Howard Ferp is a brilliant, misanthropic mathematics doctoral candidate.....Howard risks everything he thought important to save the animal and, in doing so, discovers his humanity." -- IMDB

"Jason Clarke stars as Howard, a "perpetual student" at an unnamed university, a misanthropic math whiz and chess buff whose contempt for the world oozes out of every anti-social pore. He doesn't suffer fools gladly, and in his eyes, that includes pretty much everyone, especially the old coot (Garry Marshall) who offers him no real competition in a chess tournament....Purple's film (he co-wrote the script) has a dog do what dogs do — make this inhuman jerk more human." -- Orlando Sentinel

Perhaps I'm over-reacting. I mean, certainly there are anti-social jerks, and some of them are mathematicians. The appearance of any one such character in a work of fiction is not an indication of any societal prejudice. However, this appears to happen so often that I am convinced that authors think "Well, I want the character to be horrible, barely human...I know, I'll make him a mathematician!". And, the reason this concerns me is that it would seem to lead to people I meet thinking "OMG...he must be horrible and barely human!" when I introduce myself as a mathematician. Just like any other prejudice, it can be worsened or even created whole-cloth through fictional portrayals.