Vidal writes like shit

Bought a remaindered copy of Gore Vidal's The Golden Age, and note that it doesn't seem to be said often enough that Gore Vidal writes damn nearly worse than Dan Brown. I skim through for the political snark, but how much easier it would be to take if he'd just do it straight and skip the attempt to write a novel.
The stretch and slip of the timeline in the conversations. Open at random. p.22.
Time one -
"Good evening, Mr. president." She felt for an instant that she should curtsy in the awesome presence [five lines description] Roosevelt removed his pince-nez,
Time two
worn, Eleanor had sighed, as a reminder of his political mentor, President Woodrow Wilson. "We hope Frankline won't make the same mistakes poor Mr. Wilson did."
"Such as going to war?" Caroline, like everyone else in the world, wanted to know what the president intended to do... [three lines expansion]
Time one again
"Caroline!" The resonant voice filled the room... 4 lines Tonight he was not wearing the braces. But then
Time three
he had always been at home with Caroline since they had first met twenty years earlier... (12 lines) unless the master politician was to run for a third term
Time four
"Nor will I run" he assured Caroline her first evening in the White House...
Time - hell, I don't know; one? Four?
But, so far, there was no shooting war, though she knew it was coming, and so she carefully answered his questions about the part of France where she lived...

He has all the style and grace of a chest of drawers falling downstairs. Which is odd, because he's a good essayist and a clear and graphic speaker. Why does he fall apart so totally as a novelist? I don't remember him being this bad earlier - in, say, Julian, though that does remind me that I read Julian in Thailand in 1964 and my memory for style probably doesn't cover forty years. Burr, Lincoln, that one about plato and confucious - were they this bad? I must re-dip.