Mandela was fighting to end aprtheid in HIS country. ISI is poking its nose in another country.
Mandela used mostly peaceful means. ISI is sponsoring cross border terrorism.
Mandela was motivated by love for his country. ISI is motivated by hatred for India.
Make sense ??
Kashmir isnt "another country." Kashmir is pretty much occupied territory, so ISI getting involved there is perfectly legal by your own definition..:)