Pedants would probably agree that this is a true statement, but it is also not relevant. The project itself claims it is open source and the parent claims it isn't. No one mentioned the free software movement.

Parent is pointing out that the license lacks some provisions commonly required to be considered "open source" -- a better term for what is presented might be "disclosed source" or "visible source."

Defining open source can be a point of contention, but the license in question is pretty far away from most accepted definitions. There's not even a right to modify the code. Note that this license appears to be only on the base project that seems to contain nothing beyond documentation and samples.

You're absolutely right, of course. But I never implied it was. I highly doubt this would be an OSI approved license.

https://opensource.org/faq#unlisted-licenses