This is a no-brainer. The administration finally has enough “goods” on McCain to make him toe the line. They’ve threatened him with the same level of exposure that was threatened on Roberts.
They must have had enough “goods” on him during his lousy campaign and about every moment since then, in that case.
They have nothing new on him. He’s always been a weasel and a not-very-crypto Dem, and I don’t know why the people of his state vote for him.