Yeah this seems like a good take. Otherwise it's like saying anyone building alternative or similar runtimes for existing languages is evil. This is common. People don't always contribute to existing languages or runtimes because it's fraught a lot of politics and it can just be easier to fork and do what you need, rather than trying to get what you need into a project that might not want it.
AFAIUI, it's mostly just R with better parallelisation of matrix libraries (which is cool).
It's not quite compatible, but I've used both through Conda a bunch, and haven't hit any edge cases that caused a problem.
So yeah, you're right that it's embrace/extend, but the extend was done by a startup which they bought.