I think this argument is a real non-starter, and I wish that people would stop using this ‘CCP said…’ argument without understanding what CCP actually did say.
The quote both uses the word ‘explicitly’ and puts the word ‘owned’ in quotes, and is a direct response to asking if there are any game mechanics to enforce ownership. All it says is that ‘there are no game mechanics that enforce your claim on any asteroids in space, including the ones generated by the refineries we are about to implement’.
It does not say they aren’t yours. It doesn’t say they are yours, either. It says that it is up to players to enforce or encroach on a claim, and nothing more. CCP is neither defending the right to mooch nor condemning moochers for mooching.
What you are really saying is that ‘if someone can steal it, it’s not yours’, and while that is more truth than fiction, let’s not make the claim that CCP authorized that explicitly, or denied the implied claim of a refinery owner to the ore they invested infrastructure and fuel into bringing into existence.