Plus, isn't Gwi-Ma's whole temptation thing just one big trap?
He tempts people by giving them a solution to their problems with grand, ideal scenarios only to twist it and make them suffer in the end because they fell for it.
Gwi-Ma was fully aware of how strict the king was.
but also im sorry isnt it OBVIOUS that he didnt know his family would be left behind? its not like he wanted to abandon them, he didnt know the extent to gwi-ma's deal, and the guilt ends up eating him alive anyway