I agree but it's not realistic to say that the media shouldn't pay attention to an allegation like this without a police report.
Maybe Biden's response should be, "file a police report and have it investigated then, if you're making this allegation." But I think the statute of limitations is up perhaps?
The FBI already vets every Supreme Court nominee. I believe the president's team does a very thorough background check on every possible nominee they are considering including an FBI background check. There's a difference between trying to get someone punished by law and what is investigated by Congress, or how closely they look at nominees for major posts. There's no due process in the latter. If you want a job like that anything and everything is fair game. If Congress wants to investigate something there's almost no limit, even if Trump thinks otherwise.