Burden of proof is a tragically misapplied concept. The question is what position should be the default given some uncertainty? This isn't decided in a vacuum.

Burden of proof is a tragically misapplied concept. The question is what position should be the default given some uncertainty? This isn't decided in a vacuum. The default should be decided based on the facts and utility estimates of various outcomes where relevant. In the case where the issue is of purely academic interest, the burden of proof is on those making the claim. When the issue has real world consequences, then utility estimates of various outcomes are relevant. Who has the burden to demonstrate that GoF research is safe given our uncertainty of whether COVID was lab created and subsequently leaked? This issue isn't of purely academic interest. We must consider the costs to society of a leak vs the benefits of that research. From where I'm sitting, the benefits are non-existent relative to the costs. Given the massive negative utility of a leak compared to benefits of the research, the burden of proof is on those who want to continue doing GoF research to demonstrate safety and value.