That's real convenient that you'd cherry pick an article from 1990...
4 years before he became President.
3 years before he won the Nobel Peace Prize.
Why did Madiba not renounce violence at that point?
Because they were up against a government who's response to non violent protests for the last 30 years was savage attacks against unarmed civillians.
Even against School children in the case of the Soweto uprisings of 1976 when Police opened fire using live ammunition on SCHOOL KIDS.
It was pressure from his party who had been on the outside for so long.
And worse still, was the allegations that came to light that elements of the police force were arming favoured factions of tribes to fight eachother in the cases of the Boipatong massacre and various other incidents.