lcalamar Seems a bit contrary to using GOS, but maybe I am thinking more of privacy than security?
There are as many reasons to use GrapheneOS as there are users.
The GrapheneOS developers have invested a lot of time to make Google Play Services, and thus apps relying on those services, to GrapheneOS users who want them. So it is unlikely that the developers have a consensus that using Play is contrary to using GrapheneOS.
Please note that I do not speak for the GrapheneOS project.