From that article it looks like Mbeki beloeved that the medicines were harming AIDs sufferers and not helping them. He was not trying to make them suffer or trying to kill them, he believed he was helping them.
Peter Singer says
'In Mbeki's defence, it can be said that he did not intend to kill anyone. He appears to have genuinely believed ? and perhaps still believes ? that anti-retrovirals are toxic.
We can also grant that Mbeki was not motivated by malice against those suffering from Aids. He had no desire to harm them, and for that reason, we should judge his character differently from those who do set out to harm others, whether from hatred or to further their own interests.'
Singer then says that the majority of scientists disagreed with Mbeki. he says
'This does not mean that a majority of scientists is always right. The history of science clearly shows the contrary. Scientists are human and can be mistaken. They, like other humans, can be influenced by a herd mentality, and a fear of being marginalised.'
He says that history shows that the majority of scientists are not always right.
He says that Mbeki made the wrong decision, but says that Mbeki sincerely believed in what he believed.
I agree with Singer on all of that.