How is he wrong? From your link:
Soros claimed, "The Bush administration is again committing a blunder in the Middle East by supporting the Israeli government in its refusal to recognize a Palestinian unity government that includes Hamas."
He argued that the decision impeded peace between Israel and the Palestinian people and the Middle East at large. He wrote, "This precludes any progress towards a peace settlement at a time when such progress could help avert conflagration in the greater Middle East."
The billionaire added that the U.S. and Israel’s hope for new elections to deny Hamas’ majority is "a hopeless strategy, because Hamas would boycott early elections and, even if their outcome resulted in Hamas’s exclusion from the government, no peace agreement would hold without Hamas support."
He noted that, "If Israel had accepted the results of the election, that might have strengthened the more moderate political wing. Unfortunately, the ideology of the ‘war on terror’ does not permit such subtle distinctions."
The Israeli government's refusal did directly lead to war. If Israelis had recognized a Palestinian unity government that includes Hamas, that would have given them some recognition. By providing them none, the only recourse for Hamas is war.
That does not make Hamas right in what it did to the Israelis but everything is not black and white.