Which scientific community are you referring to? There are countless scientists who have been arguing against the risks of gain of function research for many years. Why are pro-gain of function scientists deathly silent now about the supposed benefits of their research?
Which is not a dismissal at all. What scientists are saying is that both zoonotic transfer and lab leak are plausible, but that we don't have evidence for the latter (yet!) and the former is more likely.
In many media articles this simplifies to 'scientists say virus origins are zoonotic'.
Is this likelihood differential being calculated using data, or is it just a hypothesis?
I don't think at this point it is credible to assign probabilities to either hypothesis (which are assumed to be exclusive here).