Yaron Ezrahi, a professor of political science at Hebrew University in Jerusalem, said he did not believe that Mr. Garlasco’s interest in memorabilia could support allegations of “premeditated bias.” He said, however, that Human Rights Watch’s credibility might have been wounded because Mr. Garlasco’s hobby “has armed the right-wing fanatics” who “work day and night to demonize any individual or organization that raises questions about the military practices of Israel when they end up even with unintended civilian casualties.”