Allow me to provide you an actual 'needle', as opposed to a crudely fabricated one (DonS clearly was not 'defending UNITA', as the writer is obviously aware).
Angola is presently run by a brutal and oppressive regime, very much Marxist, and particularly bad at running the economy. Angola has reserves of resources comparable to South Africa, but exploits them in a characteristically 'communist' fashion - i.e. very badly, and with a maximum negative impact on the environment. Meanwhile, UNITA, no more than a rival gang to the present administration, keeps the 'revolution' alive by virtue of diamond mines fortuitously located within their area of operations.
This pleasant little situation has been the major reason why so many Angolans immigrate to South Africa for work. As to Cuban involvement in the country, the Cuban army is ideally suited for intervening in African fratricidal wars. Fidel isn't particularly concerned about friendly casualties, the Cuban have access to modern weapons (in respect to the Angolans, that is), and have a particular expertize in crushing popular uprisings, comparable to the old KGB. The South African army was successful mainly due to the vast technological advantage they held over their neighbors - this has narrowed under the tutelage of the Cubans (although not brought anywhere near parity, of course), thus making old South African tactics untenable.
Is Savimbi a nasty fellow? He certainly isn't particularly interested in democracy, but in comparison to what passes for 'government' in his home country, he's a saint. The typically nasty nature of Marxist regimes has helped this civil war to continue to the present day, and the attitudes of hard-core Marxists like Mr. Krasny have made negotiations between the government and the rebels a joke. The simple fact is that the Angolan government steadfastly refuses to treat their people in a decent fashion. Without a more refined machine of terror(as exists in Vietnam), or the patronage of more powerful Marxist states than Cuba(like the defunct USSR once was), Angola will likely continue on like North Korea - a sad, savage little anachronism, justified only by the most strident radicals on the Left. Meanwhile, the democratization of South Africa continues, fueled by the interests of capitalists in stabilizing an important source of mined resources and scarce metals. The rising wealth, education and affluence of black workers in that country, and their subsequent value as consumers, is a substantial force of change in the country as well. In ten years or so, it might be a South African army, filled in with indigenous black African recruits, that finally turns the tables on the thugs that terrorize Angola and bring in a real democratic regime. Until then, UNITA and other rebel groups (less than half of the rebels in Angola are in UNITA) make up the only hope for many in that country - and a severly qualified 'hope' at that.
Which is what Reagan's policy was all about, after all.