That's absolutely fine for them, but they shouldn't call it "Open-source" and "Fully open source" (like they do on the linked page).

This software is source-available. Open Source licenses don't discriminate on the basis use of the software.

Using the term Open Source for license like this is dishonest. It seeks to profit from the goodwill from actual Open Source software.

I can link to community-edited articles, too: https://en.wikipedia.org/wiki/Open_Source_Definition

We make the consensus reality. I'm part of the faction that wants this particular reality, so I advocate for it.

OSD !== Open Source. All OSD is Open Source, not all Open Source is OSD. You are free to disagree, but the OSI has chosen (more accurately forced to choose) very explicitly to only define and trademark OSD. There's really not much more to the conversation then that.

Maybe you're right, but FSL/BSL is arguably "more open source" than GPL. We all know GPL is a poison pill that kills commercial use, while FSL/BSL just blocks competitors from stealing your app.

That's not even remotely true. GPL does not prevent any commercial use, when others (like BSL or the O'Sassy license here) explicitly prevent commercial use...

Are you kidding me? If you link against a GPL library in a proprietary commercial app, the GPL's copyleft infects that code and you'd have to release it under GPL.

Explain to me how that doesn't prevent commercial use? Are you going to say "well technically it doesn't prevent it"? No one cares. Commercial projects avoid GPL like the plague.