I doubt it would have prevented Trump at this point. Felony convictions, sexual assault, massive fraud, and insurrection didnt stop Trump, neither would this. But as for why Biden didnt release it, who knows? Unlike Trump, Biden let the agencies do their jobs without constant political pressure and interference, he would have deferred to the DOJ doing what they thought was appropriate. Or maybe the situation is worse than any of us realize, and so many democrats and republicans are implicated that outing them and causing their arrests and expulsions would leave congress and other government agencies so vacant as to render the entire federal government non-functional. And therefore neither Biden nor Trump want to deal with the aftermath.  In any case, theres no reason to believe Biden is implicated. Theres a mountain of reasons to believe Trump is likely implicated.