This is an argument from incredulity.
I mean sure, anything’s possible, but we have only circumstantial evidence right now and this observation isn’t a smoking gun, but it ain’t worth nothing.
SARS after all was found in civets, and then later several other species as well despite originating in bats.
We can’t rule it out, ie. we only have evidence right now to try to make a determination based on the preponderance of evidence, not beyond a reasonable doubt. The story that is emerging is that we may never be able to prove something beyond a reasonable doubt because the debate was quashed for a year by political concerns, institutional biases, and motivated reasoning.