What would be the Term for this Character Trait? This might be the wrong place or way to ask this question but I'll give it a shot. It could be more related to literature but it does deal with a form of character or personality. 

In Nathaniel Hawthorne's "Young Goodman Brown", the "protagonist" wakes up from a dream (or vision, maybe even reality) of all his religious towns folk members taking part in blatant evil deeds. The next morning, his perception of everyone changes to the point he (not exactly) distrusts everyone because of what he saw and eventually dies lonely due to his callous nature. Nathaniel made this in order to warn against this type of action or character trait but what is a term for this, this trait? This callous behavior due to an imperfect/changed perspective? Is it a combination of terms?
Nathaniel made this in order to warn against this type of action or
  character trait but what is a term for this, this trait?


I think that Nathaniel is presenting a powerful indictment against individuals with borderline personality disorder (BPD). He is not saying that one should ostracise the Borderline, but that one ought to proceed with caution when choosing to becoming entangled in the lives of those with BPD.


  the "protagonist" wakes up from a dream (or vision, maybe even
  reality) of all his religious towns folk members taking part in
  blatant evil deeds.


Clearly, the Borderline is experiencing the phenomenon of dream-reality confusion:

Dream-reality confusion in borderline personality disorder: a theoretical analysis

This paper presents an analysis of dream-reality confusion (DRC) in relation to the characteristics of borderline personality disorder (BPD), based on research findings and theoretical considerations. It is hypothesized that people with BPD are more likely to experience DRC compared to people in non-clinical population. Several variables related to this hypothesis were identified through a theoretical analysis of the scientific literature. Sleep disturbances: problems with sleep are found in 15–95.5% of people with BPD (Hafizi, 2013), and unstable sleep and wake cycles, which occur in BPD (Fleischer et al., 2012), are linked to DRC. Dissociation: nearly two-thirds of people with BPD experience dissociative symptoms (Korzekwa and Pain, 2009) and dissociative symptoms are correlated with a fantasy proneness; both dissociative symptoms and fantasy proneness are related to DRC (Giesbrecht and Merckelbach, 2006). Negative dream content: People with BPD have nightmares more often than other people (Semiz et al., 2008); dreams that are more likely to be confused with reality tend to be more realistic and unpleasant, and are reflected in waking behavior (Rassin et al., 2001). Cognitive disturbances: Many BPD patients experience various cognitive disturbances, including problems with reality testing (Fiqueierdo, 2006; Mosquera et al., 2011), which can foster DRC. Thin boundaries: People with thin boundaries are more prone to DRC than people with thick boundaries, and people with BPD tend to have thin boundaries (Hartmann, 2011). The theoretical analysis on the basis of these findings suggests that people who suffer from BPD may be more susceptible to confusing dream content with actual waking events.


  The next morning, his perception of everyone changes to the point he
  (not exactly) distrusts everyone


This is a classic Borderline trait: A pattern of unstable and intense interpersonal relationships characterized by alternat­ing between extremes of idealization and devaluation.


  dies lonely due to his callous nature. This callous behavior due to an
  imperfect/changed perspective?


No, the loneliness is due to the Borderline's Frantic efforts to avoid real or imagined abandonment. Ironically, it is through this effort to escape their aloneness that the Borderline dies alone.