It is far from obvious. Linked posts show how they were stomping around a simpler logo for a long time busy with minor adjustments until someone posted a much improved logo, which just happened to be almost identical to the OP's. That was not an evolution.

But even that aside, you are viewing this situation all wrong. "Legalities", "legal ground to stand on", etc. The way Tox handled this is nothing short of peeing in a community pool. How do you envision Tox replacing Skype if the project leadership can't handle a simple dispute over a logo in a civilized manner? Look at latitude's creds, they should be wanting him on their side, but, no, let's mix him with a barrel of shit, because he dared to suggest that /gd/ might've ripped his work. Right on.