What does the bold part mean?
Chomsky's target is the BDS (Boycott, Divestment and Sanctions) movement, which has made significant strides in recent years. It calls for an end to Israel's occupation of Arab lands conquered in 1967 and the dismantling of its West Bank wall; recognising the rights of Palestinian citizens of Israel to full equality; and respecting and promoting the rights of Palestinian refugees to return to their homes.
Chomsky says that while there is wide international support for the first two goals, there is only negligible backing beyond the BDS movement itself for the return of the 1948 refugees – a key Palestinian demand. Insistence on that, he says, "is a virtual guarantee of failure".
Against a background of bitter arguments over BDS activity on US university campuses, Chomsky invokes the "glass house" principle, writing that if Tel Aviv University is boycotted because Israel violates human rights at home, "then why not boycott Harvard because of far greater violations by the US?"
He also questions the "very dubious" analogy made by BDS between sanctions against Israel and sanctions against apartheid South Africa. By 1960, global investors had already abandoned South Africa, says Chomsky, though some historians dispute the claim. Today, by contrast, US investment is flowing into Israel.
source: http://www.theguardian.com/world/2014/jul/02/bds-boycott-campaign-israel-noam-chomsky