Contrary to earlier reports, health reasons, not politics are behind Stephen Hawking’s decision not to attend the fifth annual Presidential Conference in Jerusalem in June, a Cambridge university spokesperson said Wednesday.

But the Conference’s organizers, evidently unimpressed, said they stood by an earlier statement that slammed Hawking for pulling out.

Tim Holt, media director at the University of Cambridge, told The Commentator that there was a “misunderstanding” concerning the world-renowned physicist’s withdrawal from the conference.

“For health reasons, his doctors said he should not be flying at the moment so he’s decided not to attend,” said Holt Wednesday. “He is 71 years old. He’s fine, but he has to be sensible about what he can do.”

The Cambridge professor suffers from Lou Gehrig’s disease (ALS), is almost completely paralyzed and confined to a wheelchair, and uses a speech generating device to communicate. His health has been steadily deteriorating for decades.

The heads of the British Committee for the Universities of Palestine organization had earlier published a statement on its website saying its members “understand” that Hawking declined attending the conference because of “his independent decision to respect the boycott, based upon his knowledge of Palestine, and on the unanimous advice of his own academic contacts there.”

According to a report in The Guardian, Hawking informed President Shimon Peres, the patron of the conference, that he would not be attending last week, but did not publicize his decision.

The annual Presidential Conference brings together “world leaders, international scholars, activists, poets and scientists, artists and clergy, entrepreneurs, economists and industrialists, as well as representatives of the next generation of leaders” in order to discuss issues of geopolitics, economics, environment, culture and more, the conference’s website says. This year’s conference is also a celebration of Peres’s 90th birthday.

After the initial reports, Presidential Conference chairman Israel Maimon decried Hawking’s ostensible boycott of the conference as “outrageous and inappropriate, especially for one so fundamentally associated with the spirit of independence as a person and an academic.”

Later Wednesday, even after the health explanation had been issued, a conference spokesperson said nonetheless that the organization “stands by its statement” and would not reveal any of the contents of Hawking’s missive to the president.

Hawking, who has visited Israel several times in the past to meet with Israeli and Palestinian academics, has long been a critic of Israel’s policies toward the Palestinians. During 2009′s Operation Cast Lead in the Gaza Strip, Hawking said in an interview with Al-Jazeera that Israel’s military campaign was “plain out of proportion.”

“If Israel wants peace, it will have to talk to Hamas,” Hawking said at the time. “Hamas are the democratically elected leaders of the Palestinian people, and cannot be ignored.”