Here's the source of the disagreement. You're justifying the use of the term "open source" by saying it's logical for Meta to want to use it for its popularity and layman (incorrect) understanding.
Other person is saying it doesn't matter how convenient it is or how much Meta wants to use it, that the term "open source" is misleading for a product where the "source" is the training data, and the final product has onerous restrictions on use.
This would be like Adobe giving Photoshop away for free, but for personal use only and not for making ads for Adobe's competitors. Sure, Adobe likes it and most users may be fine with it, but it isn't open source.
>The way open source software, today, generally means source available, not FOSS.
I don't agree with that. When a company says "open source" but it's not free, the tech community is quick to call it "source available" or "open core".