There are at least three gaping holes in the Al Jazeera story that render it, in effect, little more than baseless, and indeed irresponsible, speculation.
First and most importantly, Arafat's symptoms are well documented and completely inconsistent with 210PO (polonium) poisoning. Unlike Litvenenko, he didn't lose his hair and his bone marrow was found to be undamaged. He also staged at least one brief recovery, which wouldn't be possible in the case of polonium poisoning. It should be added that his symptoms were also completely inconsistent with AIDS.
Ailing President Arafat in 2004.
Second, the Swiss lab report on which the Al Jazeera story relies, clearly states that its findings are inconclusive and provide no basis for concluding polonium poisoning, especially since his symptoms were inconsistent with that. The report also states that further testing may reveal that the 210PO levels detected may prove to have been naturally occurring, albeit unusually high.
Third, the provenance of the items in question is not well-established, and therefore the relationship between the 210PO levels discovered on them and Arafat's condition is very much in doubt. Even an exhumation of the body, which the Palestinian Authority (PA) is reportedly considering, may not prove conclusive, as 210PO has a very short half-life of 137 days.
Finally, the timing of the Al Jazeera story is extremely suspicious. The PA leadership is currently embroiled in a series of controversies involving police brutality against demonstrators, suppression of dissent, potentially politically motivated corruption trials, and a growing financial crisis that has made paying the salaries of public employees extremely difficult.
The PA's woes have paralyzed its diplomacy. A recent planned meeting of Palestinian officials with Deputy Israeli Prime Minister Shaul Mofaz fell through, at least partly due to public pressure. An upcoming meeting between Palestinian President Mahmoud Abbas, Secretary of State Hillary Clinton, and French President Francois Hollande, apparently designed to persuade the Palestinians not to renew their efforts for further recognition at the United Nations, is also meeting with considerable Palestinian public opposition.
Al Jazeera has a history of trying to discredit the Palestinian leadership in Ramallah, most notably with the release of a dump of often undated and unsigned documents from the PLO negotiation support unit in January 2011. The current report, which fails to make a convincing case that Arafat was killed by 210PO poisoning, seems to be only the latest iteration of this pattern.
The core reporting in the Al Jazeera story doesn't constitute journalistic malpractice, but the sensationalism with which it is being presented is clearly designed to reignite the rumor mill about Arafat's supposedly mysterious death. But the burden of proof on those who would claim that the death of a sick, 75-year-old man who ended his days in miserable squalor following an exceptionally difficult life was due to anything other than natural causes -- as established by his doctors at the time -- is extremely high. So far, nothing, including the new Al Jazeera report, even begins to meet that burden.