I'm noticing the same problem, when I tell Google to crawl my sites and render a preview, the results are just a bunch of messed up code - this cannot be good for SEO. I didn't catch this initially with some of my other sites, because I had set up Google Webmaster Tools long before I installed Wordfence.
I will be removing this from all of my sites as well, if there aren't any official responses on here sometime soon.