Here's a bit more detail from Rick Perlstein.

You put it so nicely, Phil. Here's my version of it from a few months ago, with apologies for quoting myself to total strangers. "It's the old, "When I said you lacked basic human decency what I really meant was 'Here's a coupon for free ice cream'' defence. Notice how it expands the reach of the writer's right to talk rubbish while narrowly constraining your right to object to it. He sets the meanings, and you agree. But the vagueness of the language is also cover for an agenda, which is to get consent and countenance for the big lie (sorry, basic principle) he's pushing. Later, the reader's silence becomes "agreement for the sake of argument" which becomes "agreement" which becomes "Oh, yes, I assure you, you signed the deal; here's your signature in blood, and my Dark Lord Satan's signature right next to it, you see.""