Even The San Francisco Chronical

Thinks that Senator Dianne Feinstein's late addition of a decades past complaint of sexual assault, is less than kosher.
Editorial: A disturbing 11th-hour allegation against Kavanaugh

Feinstein, a California Democrat, took the worst possible course by waiting until almost a week after Kavanaugh’s confirmation hearing was completed to ominously announce that she had turned over “information from an individual” about Kavanaugh to the FBI, and adding that she would be honoring the woman’s “strongly requested” confidentiality.

Of course the confidential thing went out the window as soon as the issue became public.
Sexual assault is no matter for simple dismissal but the lack of undocumented substantiation casts 

serious doubt on the accuracy of complaint. Furthermore, the submission by a politically motivated participant makes it impossible to ignore the temptation to be dishonest.
As hyperbolic as social media has been, I find it interesting that there is very little offered on this topic, I suspect that this is because most people, even Democrats, think the story is bullshit.