China will not, if possible, willingly put itself in a position which admits any likelihood of losing face. If they couldn't rule out the possibility themselves and/or cover up completely that it was in fact a leak, they won't let anyone in - not because it happened, but because it might have.
That reasoning is so, so, so weak. 'This might embarrass us so you can't look' is _not_ a valid defense; anyone who says it is can be assumed to be complicit.
If it 'might' have happened, then there needs to be an investigation.
We're talking about millions dead worldwide, and tens of trillions in damages. Inequality has spiked and second-order deaths may well outnumber direct COVID-19 deaths already. And years on we haven't had an investigation into the single most likely source - that's insane, dangerous, divisive and inexcusable.
