The title is indeed wrong. There is no definition or usage of the word "open source" that is compatible with restriction of commercial usage.
Never in the history of free software or open source software from the release of Donald Knuth's TeX in 1979, to the birth of FSF in 1985, or the formalization of OSD in 1998 was it ever acceptable to forbid commercial usage in something that is known as open source.
The corruption of the word "open source" to mean anything with source code available on GitHub under a non-commercial license is very recent and does not reflect the true origin or meaning of the word "open source".
The implication that CC-BY-NC-SA could be open source seems to be your belief which is not based on facts.