Don't trust. Verify.
Even if there were something special about graphene that made it more desirable, the real way to deal with an open source project with something unacceptable about it's production or management, is to fork it. But I already have something else to do all day, and am happy to run lineage or calyx or or others. If I did need a fork, I'd need someone else to do it, and I'd have to trust them.
Fork it or help someone else who is forking it or work towards changing the original (which is what seems to have happened actually, so this is all a bit academic now), or just use anything else, are all more reasonable responses than "the people producing this thing with access to all my communications have shown themselves to be off the rails, so what I'll do is keep using it, but personally read all the code in an entire android os."
Someone else said that the head guy isn't the head guy any more so the biggest problem may not be a problem any more. The idea, stated ideal, design, & construction (as far as one can tell honestly) of the os are all fine.
But the point was, you don't need any more reason than his behavior to avoid granting him such a priviledged place in your phone, which holds such a priviledged place in your life. Just on basic principle. You don't need to justify that to anyone and he or the project does need to justify why one should trust them. The usual justification is merely the utterly flimsy weak one of benefit of the doubt. It's more or less impractical to actually vet strangers, and so you just grant benefit of the doubt until there is some reason to question. But that goes out the window the instant there IS any reason to question.
People have different tolerance for risk, and so, you might be fine with saying "that guy is acting a little weird in this way, but whatever, probably he can still be counted on in this other way.", but no one else is obligated to. And this example of "weird" was not just neutral irrelevant non-conformity.
There have been countless examples of people in positions of responsibility and trust going off the rails and taking a bunch of users down with them. There is no reason not to use your nose for what it's meant for in this way.
But like I said, maybe the problem is resolved now by the fact that we don't actually have to trust that guy any more. In which case, ok.