Not according to any well-recognized definition.
Furthermore trying to warp the definition to fit your agenda won't solve the underlying problems with the license.
Finally, github is indeed how open source projects generally discuss issues related to the project (at least as they relate to the code itself, and that includes licenses). But perhaps you are right, it isn't the place to discuss Steem.
I agree with @sneak that Steem is open source. Open source software is not the same as free software. It sounds like @dan wants free software.
https://www.gnu.org/philosophy/open-source-misses-the-point.en.html
It is correct that open source is not the same as free software. Steem is neither. See for example, clause 6 of the Open Source Definition. Steem's license discriminates against the blockchain field by prohibiting use by blockchains other than by the specific Steem blockchain. It would be similar to Apple releasing (alleged) 'open source' mobile software but prohibiting it from being used on any mobile platform except iOS. Or a mobile service provider doing the same, prohibiting the software they release from being used on phones not connected to their network. That is not open source.