[angli]

It's possible that it's more acute for him because he's not used to it, the same way someone who's lived at high altitude for years doesn't feel out of breath. Most people, I think, are affected by the presence of sad people in some way - we can control or get used to it but the raw material is still there.

[incongruity]

This would be my expectation as well. If we likened this emotional sensitivity to one of the senses, almost every sense has a diminished response, over time, to persistent levels of the stimuli. Our eyes adjust to bright or dim light, our sense of smell can quickly adapt to filter out smells that first seem quite awful, we quickly climate to a range of hot or cold water, etc. etc.

So, it seems plausible that neurologically the same sort of sensitivity and then regulation could be at work for someone who had been essentially blind to emotions and then had their visibility switched on suddenly.