Ignoring the overwhelming political entanglement and resulting bias (which is obviously a huge issue for the poll's integrity), there is no reason to believe the respondents have a well-informed understanding of the dynamics of when and why women report sexual assault.
I mean, based on available evidence, the answer is clearly ~100%. And the same if you replace "nominee for Supreme Court" with "huge and hugely contentious notoriety". Also, if it occurred ~30 years ago, I suspect that most victims would have pretty much forgotten about it. Until they got reminded by seeing him in the news.
In particular, I never knew the name of the guy who pulled a knife, while we were flirting, and threatened to rape me. Also, I don't remember the name of the woman who attempted suicide. After I got tired of waiting for a sexual relationship, and found someone else. With whom, by the way, I visited her in hospital, until she was discharged. And I never knew the name of the guy who beat the shit out of me in a park, after I'd insulted him.
I could go on. But the point is that most people arguably don't keep grudges for decades. And yes, maybe it's just that I'm a guy. And maybe rape is just so much worse that victims do keep grudges for decades.
Also, I admit that the "based on available evidence" argument is iffy. Because we only know about cases that involve notorious perpetrators. Maybe one could use FOIA to get relevant aggregate data from police. It'd be a decent thesis topic, perhaps.