Satoshi Nakamoto can be a person or a group of people or a institutions, whatever but it is an entity.
Michael Saylor is only the CEO and representative of Strategy company, so it's better to talk about Strategy as a business entity rather than about Michael Saylor as a person.
BlackRock is another big business entity and it's not good to combine Strategy and BlackRock together for discussion and comparison with Satoshi Nakamoto.
Influence of Satoshi Nakamoto has existed since 2009, as the Bitcoin founder laid solid foundation for Bitcoin launch, existence and success over a very long time that has been more than one and a half of decade. His influence on Bitcoin and Bitcoin market will stay forever and surely is more considerable than BlackRock or any Bitcoin Spot ETFs.
You put some good arguments about respective powers of Bitcoin. Satoshi Nakamoto influence is indeed basic one, it is about very structure, concept of Bitcoin that no company can alter. Companies such as MicroStrategy and BlackRock are good because they have attracted new investors and approaches but their impact rests on monetary products, not basis of Bitcoin. Their success is connected to that of Bitcoin. Although these firms are also key players, Satoshi has more basic, long lasting impact. Hence, it is much more relevant.