Different Taxes
Mark Kleiman seems a bit confused about this. When Hillary Clinton proposed a silly gas tax holiday during the primaries, the press widely reported the fact that every knowledgeable expert regarded this as absurd because the idea was (a) absurd and (b) endorsed by Hillary Clinton. When John McCain proposes a somewhat more pernicious version of the same bad idea, its badness must be ignored because it's being proposed by John McCain and nothing is more vital to the future of the American public than for John McCain's flaws to be covered up.
After all, if the press were to start reporting that bad ideas are bad ideas even when proposed by John McCain the next thing you know they'd be talking about McCain's repeated flip-flops on the central issues of our time, characterizing Wesley Clark's attacks on McCain correctly, etc. And we can't have that!