You are right that they are making something new available, but they are not open sourcing it according to the commonly accepted meaning of the term -- and the original article actually says "... any software under this new license is non-open source by definition".
Now you might think that commercial use is a small semantic detail. But it is one that the open source / free software community has always insisted on, up to and including left-loonies like Stallman.
Of course none of this means that it is wrong or unfair of RedisLabs to do this. It merely means that what they are doing is not open sourcing anything.
On one hand I admire RedisLabs for acknowledging what all major cloud vendors are doing... embracing and extending open source packages but not giving back enhancements.
On the other hand, the terms of "commons" are not in the spirit of the license and software they've built their business upon.
If in the end Salvatore Sanfilippo were getting funded by the licensing of commons modules, I'd be less concerned.
Best I can infer, they want to open source the module, but not compete against themselves if others get into the Redis cloud hosting business.