Their point is that if you have the money to buy $1.1B of something off market, you should also have the money to buy $1.1B of something on market. Any time someone posts an ask at or below $22, you simply fill the order.

beyond the fact that the dynamics of saying "we'll take everything at a certain price up to $1.1B" will likely lead to much more than that showing up on the market and leading to a price crash anyways... I imagine that an off market transaction can involve things like not sending $1.1B in cash to the other person the same day.

If you have enough assets, everything can show up, and you just buy them out.

It's describing an arbitrage opportunity. If person A wants to buy something for $5.00, and person B will only sell for $1.00, I stand to make $4.00 per unit by simply being a middleman for the transaction. Private or public markets, the arbitrage opportunity remains the same.