I don't think that has to be the case. There are a lot of objective standards you could apply and tests you can do.
For example, as a somewhat bad example, ask people if they trust vaccines or not, and if not why not.
Epistemology and non-binary logic are not just complex, they're counterintuitive.
However in this case, your excellent "and if not why not qualifier" could possibly save the day...but then it comes down to whether the judge doesn't get it wrong.
Not wanting to get the vaccine is not the disqualifier, but the reasons justifying that decision could be.
Truth and agreement at the abstract level where we're working right now is easy, but the move to the object level is anything but (even though it seems easy).
People of good repute with the necessary qualifications to understand scientific findings.
Really, that's it. We're mostly just trying to stop the cuckoo fox news/alex jones crowd from voting and for good reason.