But is there not guilt by association according to Scripture?
No... while I understand what you're saying, it's a logical fallacy.
Does not Warren ignore/disobey the direct command of Romans 16:17 and does he not also fail to protect the sheep from false teachers and their false teachings (Manning, Nouwen, Merton, Campolo, Mclaren and etc. can all be found on www.pastors.com by quote, book endorsement and/or etc.)?
Do you not think that it is important for pastors and the church to keep away from false teachers and their false teachings?