It’s not vague at all. Engage in an insurrection, you can’t hold office. Trump incited an insurrection that was broadcast on national television.
Biden hasn’t incited an insurrection, but if he did, he would also be ineligible for office.
The problem with Republicans is they actually don’t give the smallest shit about the law or the US Constitution. They’re fascists, the don’t have integrity or values, except to value seizing and maintaining power, by any means necessary.