Blackrock doesn't need BTC to profit on the markets. They already own a large chunk of the equity market.
Secondly, they don't want to have a directional market risk on Bitcoin (the one that usually triggers the stop ): they are hedgers, not traders.
They would make enough profit from management fees, without putting in place risky positions on the market).
That's likely true, but if they had insider information that their ETF would get approved, and since we almost certainly know that it would have a positive impact on BTC price, then there's not much risk on their side. Also considering that the entire Bitcoin involvement is just a tiny fraction of their operations.
$1.4 billion of net profit after tax just for the last 3 months and over $9 trillion of average assets under management is truly impressive. You don't get bigger than that.