According to Ed Morrissey’s source in the McCain campaign, yes. (Via Instapundit.)
The allegation isn’t exactly solidly sourced, but is it plausible? I guess the matter comes down to whom we think is more respectable, the New York Times or an anonymous source cited by Hot Air. Tough call.
UPDATE: It’s not proof that they made the threat, but if they did, they followed through on it.
Internet Scofflaw 