It's an interesting database. Regarding closed source complaint, it's part of a false dilemma that keeps repeating unnecessarily: that one must choose open + free or closed + paid. Nonsense! You can have open source and proprietary licensing simultaneously. You can even let paying users extend it as Burroughs did for MCP OS in 60's. I go into more detail here [1] on various models of source sharing and security review implications (my focus).
So, he could patent any key technology, publish the implementation with copyright protection, give source/binaries to customers on condition they keep paying, let users extend it for internal use, and even let users submit such improvements for others to use.. His company continues to make money on the licensing in each of these cases. All of this has been done before. If anything, the real risk is on the users that the source license might change like what happen with QNX. It's why I advocate perpetual licenses for a given release at a given rate which are re-issued each year a client pays.
[1] https://www.schneier.com/blog/archives/2014/05/friday_squid_...