so... one guy out of hundreds interviewed, and who was never personally accused by Waxman of being manipulated by the White House, claims the Bush Administration didn't in fact influence him...

where's the story?
Waxman never said this guy changed his testimony. But you can't deny the White House attempted to have scientific conclusions and testimonies by many people withheld or modified to fir White House policy.

FTA: The Waxman report details an e-mail from Tom Jones, a staffer for Alaska's Republican Sen. Ted Stevens, that he wrote to Noel Turner, an employee in the Office of Legislative Affairs at the National Oceanic and Atmospheric Administration, in the days leading up to the hearings. Jones apparently wanted Mayfield to say that global warming was not making hurricanes stronger.

Where do you see in that article that anyone accused Mayfield of being pressured by the White House?