You can't have it all, forever -- the tech is there for anyone to fork and improve, build new businesses (!), inspect, etc. F/OSS is basically a miracle as-is.
If we compare the current state of the world to one in which they were acquired and then continued to put out more F/OSS, things look bad (which I assume is your implication). I choose to instead make the comparison to the world where we never see this tech and it stays proprietary. Sure, eventually someone in F/OSS might have gotten around to building this solution, but they pulled forward the future and we get to see and build on the result for free.
If we compare the current state of the world to one in which they were acquired and then continued to put out more F/OSS, things look bad (which I assume is your implication). I choose to instead make the comparison to the world where we never see this tech and it stays proprietary. Sure, eventually someone in F/OSS might have gotten around to building this solution, but they pulled forward the future and we get to see and build on the result for free.