There's nothing to stop, because it's perfectly legal; see here
This is what would happen if the proposal becomes a site:
Q: What happens with existing Stack Exchange sites?
We don’t want to harm any communities that have already successfully gotten off the ground. This harks back to our corporate goal:
Make the Internet a better place to get expert answers to your questions.
Community is hard to build, and we want to work with you to preserve it if you’ve already done that with Stack Exchange. If we closed down or competed with the existing, successful Stack Exchange sites, that would conflict with our goals.
- Existing Stack Exchange sites will be kept open, under existing rules, for at least three months, and at least one year if you have an active site (defined as ten or more active users per day).
- You will not have to pay for these sites, ever.
- We’ll give you at least 3 months notice before shutting down any site.
- We’ll always make your data available for download.
- If your site remains very active, we’d love to work with you to migrate it to the new, community-owned Stack Exchange platform. That would be the best thing that could happen to a Stack Exchange 1.0 site, in our opinion: that way your site can take advantage of our existing resources and expansive community.