namely, that they agree to make the source code of the modified version available to the public.
TRUTH Social did not do so.
Is it clear that they they modified the source code? How do we know this?
I ask because typically, when one uses open source code it is because of its utility as a good, proven out, off the shelf installable package. For instance, if you install apache, the most commonly used web server in the world, it is extremely rare for you to modify its source code. You configure it, yes, you might install additional functionality in slotted locations, you might even write your own package of additional functionality to hook up via the provided API.
You really almost never have any reason to be modifying the web server itself, and I’d be extremely suspicious of any hire who wants to do so: you’re paid to get the job done, not to tinker. Its a bit like hiring a guy to build your deck, and he wants to do some genetic engineering to grow the right wood. You’re like, uh, no.