He is producing JSON, just as you said. Not sure you understood him.
He has a TS script that outputs JSON, which he is using as config.
He has a TS script that outputs JSON, which he is using as config.
He might trust his code, but I was highlighting reasons why this is not true everywhere, and indeed the ability to evaluate untrusted code can open up previously unavailable avenues. For example, storing server-side Jsonnet that can be safely evaluated by a multitenant backend.