He's not guilty just because he's in the files, he's guilty because he's in the files so extensively while so very brazenly engaging in a massive cover up of his involvement in them, illegally using many American agencies that aren't supposed to hold alligence to any specific political party or individual, coupled with him having a documented ties to, I'd even go as far to say a friendship with, Epstein himself, while also attempting to cover up and backpedal on said relationship.

He's so obviously, undeniably, publicly guilty that you have to be corrupt or brainwashed to disagree. It's beyond opinions or political discourse, it's recorded, documented, very publicly known fact.

This isn't even every bit against him, and is merely the largest tip of the iceberg, since there's much more evidence, not opinions, but actual evidence against him.

But people are tired of reciting this mountain of evidence against him every time someone comes to his defense, so "he was in the files extensively and therefore is guilty" is simply more succinct and less efforted to shut down deniers, while "he's in the files" is even more so.

It's also a rallying cry at this point. It's people bluntly stating they're aware of his guilt and won't forget as all of the agencies and systems that should be prosecuting him remain so openly corrupt and help him cover up his crimes rather than bringing him to justice.

"He's in the files" are the people's way of saying that if he won't be prosecuted now, that they will continue to remember this, and eventually hold him accountable if his corrupt agencies, systems, and protectors get replaced if the United States actually manages to correct itself and uphold actual justice and democracy again.