Now we found the source of the source of Brian Whitaker's tweet

So apparently the newspaper in question was Ad-Diyar.  But Ad-Diyar did not talk about defection per se.  But still: this is Ad-Diyar. It is indeed a propagandist sheet for the Syrian regime in Lebanon but for several years between 2009 and 2011, it received money by the admission of the owner, Charles Ayyub, from Prince Bandar bin Sultan.  But he said in his second visit to Saudi Arabia, Bandar would not see him and would not give him money.  As far as newspapers are concerned, it is the equivalent of the National Inquirer--only less reliable.  So relying on a Saudi site that relied on Ad-Diyar, is like relying on George W. Bush who in turn is relying on Joe Biden to answer a deep philosophical question. If the story was damaging to the FSA, Brian Whitaker would never ever had accepted its reliability.  (thanks Rupert)