Git is a registered trademark, I don't see notice of permission… maybe they didn't ask and might not have it?
Also, it's entertaining to me that in one comment you say that closed-source proprietary software is bad, and in another comment you're concerned about whether they follow trademark law. I understand that it's not a direct comparison and open source software is still subject to IP law; it's just that the juxtaposition of your comments is a bit silly.