It is akin to saying "Pliny the Younger didn't die in Pompeii overtaken by a volcano because there is so many other cities he could have died in and other causes of death." Statistically, that would have been true, up until we learned that it happened. Then the low probability ceases to matter, since it becomes an observation.
Statistically, this is due to both priors rising, proportional to their original values, such that now the sum P(lab escape)+P(natural cause) == 1 and their average is a coin-toss (50-50). So without outside information, the prior statistical probability isn't low: it is exactly neutral between the options.
We've also seen viruses arise in small villages. This is even more unlikely to be predictable in advance which village with p << 0.0001.
Exactly, that's what I was getting at - the prior for lab escape is low, but given that the pandemic happened, it the posterior for lab escape is 1 - posterior for natural.
And we had about as many examples for lab escapes as for natural epidemics in the last few decades, it seems to me.