Yes because Redis Labs is doing basically what we agreed was not in the roadmap of the open source for years... It's not a coincidence, we basically thought that there was potential in the intersection of: (what customers asked /\ what I was not going to do). But the blog post is not defensive, I think that the discussion that started from this Redis licensing thing is truly interesting, and that "open core" is a flat way to classify certain scenarios. Usually it captures well the idea, but certain times not. For instance imagine if Redis Labs would just specialize in writing orchestration software to sell Redis as a service... It's hard to argue that this would be an open core model. And what Redis Labs is doing is kinda that in a different way, to add value outside the space of the OSS project main focus.
It seems to me that the main source of confusion is about the independence of Redis from Redis Labs.
To you Redis is an independent open-source project, to which Redis Labs generously donates your salary so that it you can work on it full time.
But to most people online, that is not immediately obvious: because of the company name, you working at Redis Labs, and them being the main sponsor, Redis is seen as the "open-source core product" of Redis Labs. https://redislabs.com/community/oss-projects/ also strongly leaves that impression - it even says that to contribute to Redis you have to sign the contributor agreement with Redis Labs.
Once you have that impression, it's natural to assume that Redis + Redis Labs modules are part of one product family, and that the roadmap for both is being planned based on the business goals of Redis Labs.
Redis labs website describes itself as the "home of Redis" and sells a product called "Redis Enterprise". If that doesn't sound exactly like textbook open core, I don't know what does.
