The WIV is not a bioweapons laboratory. It's an academic research institution. Any gain-of-function experiments they would do would be aimed at understanding viruses, not creating weapons. They would use known backbones, not a virus nobody has ever heard of, that they've never even uploaded to a database.

I'm going to suggest to you that the reason you don't find the reasoning in the debunking to be solid is that you don't understand the field very well. I don't know what your specialty is, but imagine someone who has no experience in it. They might have a lot of weird conceptions about your specialty, they might have no idea how things work in your field, they might find a lot of things surprising. Things that you find obvious might seem dubious to a novice. The arguments made in the debunking are considered very strong by experts in the field. That's what matters.