Nobody ever heard oracle scrambling for cash.
You can remove that freedom to the user. After all, the source is available, it can still be tested for malware, but your work won't be open-source.
> All sorts of development can be funded with a Software Tax:
The GNU Manifesto arguably concedes OSS won't make money
> In the long run, making programs free is a step toward the postscarcity world, where nobody will have to work very hard just to make a living. People will be free to devote themselves to activities that are fun, such as programming, after spending the necessary ten hours a week on required tasks such as legislation, family counseling, robot repair and asteroid prospecting. There will be no need to be able to make a living from programming.
The moment Babel actually has to be sold for $1 is the moment it dies and everyone still using Babel switches to alternate compilers.
The project is surviving on fame, and donation's the easiest way to fund that.