Id agree with that. Sometimes people use it in ways even they don't agree with, but would agree that it's more accurate than just straight "closed source". Is source available "more open" than something completely closed?
The latest Unreal for instance. It's not closed source, because you can in fact see the source, and it wouldnt be fair to compare it to other engines/games that are just a pure black box. But yet, the licensing is restrictive. So its not truly "open source" but Ive heard some people call it open source meaning "not closed" when in reality it is somewhere in between - "source available".
In those cases, the definition is not really as important as people seem to make it out to be. I'm speaking casually and colloquially here.
And I would say that Gitlab CE is open source. And consequently, Gitlab EE is MOSTLY open source. From my understanding, its essentially gitlab CE with some closed source plugins. I dont really care where they make their money. I interact with Gitlab CE primarily, and it is the core product. Calling them an open source company is not like calling Microsoft an open source company "because microsoft has some random open source products".
My entire point being that getting bent out of shape over minor semantics is weird. Not 100% of gitlab is open source, and they make most of their money off that closed source bit, but I would venture to say that most of their users (by volume, not by revenue) deal with the open source part only.