Aside from what I said, for example, GoF research generally introduces silent mutations at about the same rate as natural evolution, because it's experimental evolution after all. Likewise, such research often implies loss-of-function, due to uneven selection pressure (unless you do GoF in humans, which isn't really needed in a pandemic scenario).

But on the other hand, he raises the point of the low level of silent mutations, which is more a case of genetic modification than GoF, and doesn't even mention the possible loss-of-function.

So even though the lab leak is plausible, she's using arguments that contradict each other, knowing that at least one of them is invalid (most certainly the GoF one).