From the article:

So you were defining yourselves in contrast to the “African socialism” that was the official state ideology of Tanzania?

Exactly. Remember, before I went to the university I was a pure nationalist, and very enthusiastic about Ujamaa, the African socialism espoused by [Tanzanian President] Julius Nyerere. But as I began reading Marx and other Marxist literature, I learned that this was a rubbish type of socialism, similar to what was introduced in England during the nineteenth century by Robert Owen and so forth, what Engels called “utopian socialism”. That’s when I broke with Nyerere, because he lacked a scientific understanding of capitalism and of oppression and exploitation.