Sirhan Sirhan was born in Palestine. but lived most of his life in the United States. Palestinians are not collectively responsible for what he did in the Ambassador Hotel pantry that night- it is likely that Sirhan inflicted the non-lethal wounds suffered by the other four shooting victims, but there are still questions as to whether he was actually the person who fired the shot that killed Robert Kennedy, or whether someone else fired that shot, or whether he was in a conspiracy to assassinate the senator.
And Sirhan's supposed motive for assassinating Senator Kennedy- his support for Israel-doesn't hold up. Other than George Wallace and Eldridge Cleaver-minor party candidates from opposite ends of the political spectrum- ALL U.S. presidential candidates in 1968 were equally "pro-Israel". There was no greater reason for Sirhan to have sought to kill Senator Kennedy than for him to have tried to assassinate Hubert Humphrey, Eugene McCarthy, Richard Nixon, Nelson Rockefeller or Ronald Reagan.
In any case, the assassination of Robert Kennedy occured fifty-four years ago and at least 85% of the current Palestinian population weren't even born then.