The open source issue is fixed, it is called AGPL.
However, the issue that Redis along many other suffering from is called brutal competition, it is not even just tech or open source tech, Amazon is eating everyone's lunch. I don't have any idea how this problem can be solved.
But, I know that restricting building API compatible software is not a solution, not a good one at least.
Letting anyone build API compatible software is a natural order of things that enables innovation and helps consumers avoid lock-in, specially with stagnated software, this is a big deal and something that we shouldn't give up, so on that topic, fark Oracle.