If your mom/wife/daughter etc. were in this situation, would you want them to immediately go to th police or not?
That's a very, very difficult and personal decision that will be affected greatly by the specific details of the situation. Details that we do not have here, that we likely will never have.
Ask yourself this: if a woman close to you were a victim of sexual assault, would you believe them? If yes, would you hope and expect that the people in your community would believe and support them, also?
The frequency of rape and sexual assault is wildly out of proportion to the number of rapes and sexualt assaults that are ever reported, let alone prosecuted, and the vast, vast majority of rapists are never convicted.
Unless you think the vast majority of people who ever identify as victims of sexual violence are just looking for attention, or money, or revenge, you have to admit that the disparity between incidence of sexual violence and reporting / prosecution / conviction is a problem.
Are you a part of that problem, or are you a part of the solution?
Since you can disagree without calling me an animal, do you perhaps have a link that could potentially show me why not going to the cops after an incident like this is actually rational?
It's probably not a rational decision.
Are you familiar at all with post traumatic stress or its symptoms? Are you familiar with shock? With depression? Self-hatred?
All of these things can contribute to somebody who is a victim of sexual violence choosing not to do anything about it in the days following an attack. They might not admit to themselves that they have been a victim of sexual assault, let alone tell another soul or go to the police.
A big part of that is we as a society have not done a good job of making people who are attacked feel that they will be believed and supported if they do tell some one. The messages out there, overwhelmingly, are that people who are raped did something wrong or even deserved to be attacked, not to mention that they are tarnished somehow by the attack (particularly if they are women).
Ultimately, the answer to your repeated question is: It's none of your business. You don't know the details, and you never will.
The important question here, again, is: Are you going to show that you will support those who believe they have been attacked, or are you going to join the multitude that says, directly or indirectly, that they will not?