The sequenced genome is freely available to all to look at, and compare to other genomes. While gene editing is not my field, if SARS-Cov-2 looked obviously man-made, I don't think any single institution / country could stop an international community of scientists from talking about this. If the evidence of gene editing is more subtle, I suspect it will simply come out in time.

Also, there is already a paper looking at whether sars-cov-2 is man-made, published in one of the most prestigious scientific journals in the world (not American):

https://www.nature.com/articles/s41591-020-0820-9