Well, you stated something along the lines of an empath being someone who could just be sensitive because of trauma. Naturally, children are wired to adapt to their environment and survive, that is as far as I know the strongest impulse they have because at such an age they are mostly concerned with self satisfaction of immediate desires. Therefore they may learn or try to learn how to pick up emotional signals from emotional abusers to avoid immediate pain. An adult may try to endure short term 'pain' or 'discomfort' from confrontation or find some complex strategy but children often just use the short term method due to the fact that they aren't that developed on an intellectual level.
Anyway, having stated all of that, if the psyche of a child is wired to 'always understand what makes someone ticks' for the sake of self-preservation, the use of reading body language which is an inherent skill in many mammals would be given a high priority, and the exercising of it may be put on a subconscious level, as it is tantamount to 'survival' or a very strong behaviour (in this sense being an empath can be considered perhaps a pathological behaviour, and many struggle setting boundaries because of this).
I don't know if the person in question had a childhood where they had to constantly read people's emotions to survive or if they inherited genes that gave them an advantage in this area, but I do believe that the circumstances I have explained are a valid explanation for interpersonal communication skills at the level of what would be considered ESP.
As for sensing emotions long distance, I believe it is very possible.
http://www.light-hearts.com/rainbow5.htm <--- this is an example of telepathy from long distance between parents and even adoptive parents. I believe that if such an awareness of others was necessary for survival at a young age or in a rough environment, it may be developed for the sake of survival, as that is the basis on which behaviour is formed for many, many people.
In that sense, empaths may not necessarily be 'good', as much as they are survivalists. If there is a good person, that is probably someone who overcomes their pathological behaviour to do what is 'right' whatever that is.
Well I went off again on the reply that ending seemed like the ending of an essay gotta have that cherry on top.