The thing that bothers me, and I can't get past, is that Hur said that he would have prosecuted Biden but for the fact that he would have trouble getting a conviction because Biden the project an avuncular aura and along with his cognitive issues, would thus prove to be a sympathetic witness. In short, Hur's commentary about Biden's cognitive issues with certainly not gratuitous, but rather central to his decision not to prosecute Biden.
He had no evidence to prosecute Biden but since he's a politcal hack, he needed to lie and salvage something to besmirch Biden.