Isn't he still pretty involved in the project? I only followed the Rossmann story for a bit until I encountered random attacks on microg in the issue for Mozilla Location Services shutting down.
There's also this random attack on alternative location services by GrapheneOS.
https://grapheneos.org/articles/positon-location-service
(Some surrounding discussion on the article can be found here (microg issue for MLS retiring))
Overall, Graphene does not seem like a friendly project in my opinion.