From the OP:
So... when did either of those things actually happen? Because what you've linked here only shows that the Davis campaign is saying that Greg Abbott is refusing to answer whether or not he would defend a ban on interracial marriage, either in the case that one was law now or previously, and that's true. The Abbott campaign
is refusing to answer that question, and the candidate doesn't deny that fact. He was asked the question in an interview by the San Antonio Express-News editorial board [See:
http://www.expressnews.com/news/news_columnists/peggy_fikac/article/Is-there-an-echo-of-the-past-in-the-ban-on-gay-5833451.php] and he twice declined to definitively answer whether or not he would/would have or wouldn't/wouldn't have.
Going from there to Davis saying that Abbott would ban interracial marriage, or Davis saying that there's a threat to interracial marriage, is a big stretch. For the moment the campaign is simply noting, correctly, that Abbott is choosing not to answer what should be a pretty easy hypothetical question.
It is a non-question. I wouldn't respond to a request so stupid. That is settled law, the SCOTUS ruled on it, and they have force majeure.