They could just create a custom license based of Apache 2.0 that allows sharing but constraints some specific behavior. It won't be formally Open Source, but will have enough open source spirit that academics or normal people will be happy to use it.
I wouldn't worry about that if I were them: it's been shown again and again that people will pay for convenience.
What I'd worry about is Amazon/Cloudflare repackaging my model and outcompeting my platform.