They’re already bundled in Discourse here: discourse/public/images/emoji/twitter at f6d97eef0829e3392b98359b48ddd253f7f8fc2a · discourse/discourse · GitHub
These are already open source, so twitter can’t un-open source them or do much damage retroactively… I guess in the event that they stop making new ones we’d have to look to forks like the one @manuel mentioned.