Marc Ambinder Says That $5,000 Might Be Greater than $12,000!

The Atlantic Monthly death spiral watch continues, as Marc Ambinder gets himself deep into "opinions on shape of earth differ" territory:

Marc Ambinder: Fact-checking Obama: First, CBS News's Wyatt Andrews reports on a charge that Barack Obama often makes about John McCain's health care plan: that it will result in tax increases for tens of millions of Americans. The truth is that it... well, it might not--although McCain would require Americans to begin to pay taxes on the health benefits their employers provide to them, some analysts think that they'd get more than that money back in the form of the refundable tax credit that McCain is proposing.... [T]he money McCain would give employees might not cover the cost of the premiums which average mroe than $12,000 per family. And one reason for changing the tax incentives is to put the kibosh on the employer-based system.  Non-partisan analysts don't think McCain's plan would expand coverage...

Question: Does Marc Ambinder so ignorant that he does not know that McCain's tax credit maxes out at $5,000, which is less than $12,000? Or is he so mendacious that he thinks it important to hide that fact from those of his readers who don't already know it?

Why oh why can't we have a better press corps?