People are using the word differently, and the community is telling them to stop using the words differently because it's misleading. What exactly are you arguing, that community should not do that? That, you know, the open source community should not tell people to stop using the term "open source" incorrectly?
But, no, I’ve quite clearly stated you can argue they shouldn’t use that definition. But you cannot credibly say that their usage is wrong if they are successfully communicating with others using that definition.
The word will change usage, or it won’t, and neither of us will probably have any say over it.
You can use your words in whatever way you want with whatever people you want, but can't deliberately ignore the widely-adopted definitions because "language changes" and claim everyone else is wrong and your microcosmos is right. Wake me up when language actually changes (i.e. when the majority adopts the new definition) and then we'll talk.
There’s literal dictionaries that disagree with you, so plenty of credibility to the alternative meanings.
I certainly do not recognise any charity’s right to define a word, so it is not official to me - or, apparently, to the OED or Wikipedia, and I would bet most other dictionaries and people.
Most people in the open source community recognize OSI definition as authoritative. "Muh assumption" - if you want data, look at the comment section in this article, most people disagree with you. You may have your microcosms of people who don't know/don't care about history of open source/free software, but your ignorance doesn't grant you any authority over language, either.
Use the language any way you want, but stop throwing tantrums when people rightfully tell you that you're using it wrong.