I agree on this. Blackrock and MSTR don't own any Bitcoin personally; they're merely intermediaries for individuals or institutions, so they won't have much influence. Meanwhile, Satoshi is a form of personal ownership that we don't know whether he'll use or not, because that's his right, and so far, it seems his Bitcoin will never be used.
And honestly, we don't need to compare them, although the OP has a fear of them influencing the market.
Blackrock has never said they have personal Bitcoin but I refused to admit they don't have any Bitcoin. They really do but wouldn't admit for some reason. Microstrategy doesn't have personal wallet but Micheal Saylor who is the founder of the company has about 17k of Bitcoin which he claimed to bought cheaper. If I'm him and it happen that I have that amount of Bitcoin, I will take speaker and walk around the street and convince everybody to understand what Bitcoin is all about.
Satoshi has built something so good that if he comes back online today and say he is not going to touch that Bitcoin alot of people are having headache, he will get plenty of donations from people that is going to be worth billions, I remember when Silk road founder was release from prison and all his Bitcoin was seized but the community help him to get some Bitcoin even though he never asked for it, that's how selfless the Bitcoin community is for everyone.