If his signature here means that he thinks it could be a lab leak and should be investigated (caveat because he might have other reasons for signing), then that is decent evidence that a GoF lab origin is technically possible.
If he signed because he found the public pressure to sign high enough that also tells us something about his assessment of the current situation.
If he signed because he found the public pressure to sign high enough that also tells us something about his assessment of the current situation.