> you can always refuse to cooperate with the investigation later, and they'll be obliged to drop the charges
This is completly false at least in the US where this story is happening. You don't decide to press or not to press charges. The presecution can decide to go ahead or not, no matter if you cooperate or not and no matter what you desire, they have no obligation whatsoever.
This is true but in a case where the bulk of the evidence is the victim's testimony, if the victim doesn't cooperate, the state will focus prosecution efforts on cases they have a better chance of winning
This is completly false at least in the US where this story is happening. You don't decide to press or not to press charges. The presecution can decide to go ahead or not, no matter if you cooperate or not and no matter what you desire, they have no obligation whatsoever.