There should be a distinction between FOSS and OSS. Nobody is trying to infringe on your FOSS rights. But some may argue the term OSS has changed to not strictly mean FOSS. The term "open source" at face value only implies "source available" until you read the license.
Ask 1,000 developers and I'd bet real money the majority would say projects under BSL and other non-"OSI approved" licenses are "open source." Not FOSS, but OSS.
In my experience most people think of open source as free plus source available. The average user doesn’t care much beyond that, which is supported by people’s willingness to add just about any dep to their software without validating licenses. No one will ever agree on terminology, but for me personally BSL is in the same category as GPL in that it achieves a bunch of the core principles, has less consequence, but also only works for certain types of software (eg sentry not libcurl).
No. Opinions are opinions and facts are facts. Mixing them up is a type error.
It is not an "opinion" that if someone were claiming that there is widespread agreement of a distinction between "Open Source" and "open-source" (or "open source") then that is untrue—because that's how facts work: they are either true or they are untrue.
It's my opinion, for example, that you guys are willfully dishonest and just kind of scummy, and so it is my opinion that neither I nor any company I work at now or in the future should ever do business with you.