I'm not sure it's correct, since they're reusing mastodon they should be clearly indicating that parts or all of the work is licensed under AGPLv3. And the claims you quote seem at best weasely if the entire thing is derivative of mastodon (and thus not in any way owned by truth social).
Per my reading of the AGPLv3 (though IANAL), section 5 seems to be rather thoroughly violated:
5. Conveying Modified Source Versions.
You may convey a work based on the Program, or the modifications to produce it from the Program, in the form of source code under the terms of section 4, provided that you also meet all of these conditions:
a) The work must carry prominent notices stating that you modified it, and giving a relevant date.
b) The work must carry prominent notices stating that it is released under this License and any conditions added under section 7. This requirement modifies the requirement in section 4 to "keep intact all notices".
c) You must license the entire work, as a whole, under this License to anyone who comes into possession of a copy. This License will therefore apply, along with any applicable section 7 additional terms, to the whole of the work, and all its parts, regardless of how they are packaged. This License gives no permission to license the work in any other way, but it does not invalidate such permission if you have separately received it.
d) If the work has interactive user interfaces, each must display Appropriate Legal Notices; however, if the Program has interactive interfaces that do not display Appropriate Legal Notices, your work need not make them do so.
Truth seems to violate:
- 5 (a) by not having prominent notices that it's a Mastodon fork (assuming there's actual divergences from mastodon aside from the —— illegal —— white-labeling modifications)
- 5 (b) by not indicating that parts of it (and which) are under AGPLv3
- 5 (c) by not providing licensing terms for the mastodon derivation it must license out
- 5 (d) by having actually removed existing legal notice entirely