They already can manipulate BTC price in any way.
This is not true.
I'm not really sure.
A large amount of Bitcoin is in the possession of a trader whose sole interest is price oscillation and making a profit from it. Maybe they don't have that much strength for sensitive manipulation right now, but they are moving towards it.
I agree with the OP statement that this ETF, Blackrock crap is not a good thing for Bitcoin in the long term