Stephanie Drury of Stuff Christian Culture Likes posted an image from a members-only Mars Hill page on Twitter a short while ago. The post is from 13 days ago, and it alludes to the plagiarism scandal without directly mentioning it:
Today in the Driscoll Plagiarism Saga™: pic.twitter.com/sLKwcQlfDZ— Stephanie Drury—SCCL (@StuffCCLikes) December 31, 2013
It seems as though the December 18th statement from Tyndale House is the one to which Driscoll is referring. I don't know if I've ever seen someone publicly express so much concern for something he's not willing to talk about.