What is the motivation behind research that makes viruses more suitable for humans anyway? I assume it's not strictly a military project, since there was international cooperation between countries that aren't allies. What is it we're tying to achieve?
Better understand the mechanisms involved in order to have better tools to fight against it, or better surveillance tools when sampling? (e.g. have a better idea of whether a wildlife pathogen is approaching zoonoticity)
Same reason black-hat security research exists. By developing a virus in a contained environment, you can study it, model it, potentially develop mitigations or cures.
Probably has no relevance for the research in question but viruses are a very effective way to deliver CRISPR-based therapies.
It's conceivable to implant the mRNA of a vaccine similar to what was used for COVID-19 into a transmissible virus and inoculate (or kill) large segments of the population.
