IKs kids are in London because of his unique family setup. His wife is British, and they have agreed not to fight over custody. From what I understand, IK has a decent relation with his wife even after divorce, so they have a sensible understanding on whats best for their kids.
NS’s son is in living it high in London on dirty money. Its no secret that NS has transferred billions out of Pakistan at various points in time. Its not the fact that he is living overseas. It is about the nature of his money.
Imran Khan made MOST of his money overseas, and brought all of it Pakistan.
NS made ALL of his money in Pakistan, and almost all of it is sitting overseas. Same holds true for his sparring partner, Zardari.
If Imran is focusing on NS, its because Punjab is the main battleground. 60% voter base.