When confronted, the Egg NS team initially denied any wrongdoing, then claimed they had "reverse-engineered Yuzu independently," which is legally permissible in some jurisdictions but does not excuse GPL violations.
The relationship between Egg NS and GitHub is primarily defined by community efforts to analyze its origin rather than an official open-source repository from the developers.
GitHub provides incredible infrastructure for legitimate open-source emulation (RetroArch, Dolphin, PPSSPP, etc.). But it also enables bad actors to launder proprietary code under an open-source veneer. GitHub relies on DMCA notices and community reporting, which is reactive rather than proactive.