Nobody is thrashing this kid as he does not have experience of how to handle these situations. In general, in later stages of GSs, one tends to play. For example, Cilic played out the whole match despite blisters in last Wimby, because he knew it is considered terrible to retire in the final of GS, unless absolutely necessary.
This being SF and considering blisters is not a deadly condition, I think Chung should have at least waited until the second set is over before quitting. The only reason, he did not do so, I believe, is that being young he did not know the proper etiquette. So, I would not blame him.