When this came up on HN before, it looked like the argument was premised on the divergence between RaTG13 and SARS-CoV-2 -- it's not reasonable to think some lab started from RaTG13 and ended up with SARS-CoV-2. It's a very long reddit thread and I'm not a biologist, so it's hard to be sure. But on that understanding, my objection is "WIV had many unpublished coronavirus samples, and took their database offline in fall 2019. RaTG13 is just the least distant relative to SARS-CoV-2 that they did publish." as I said last time:
https://news.ycombinator.com/item?id=26756618