Instead, I installed CalyxOS and have been using it over a year now and I'm very happy with it. Check it out.
You have to be aware that you give that person root when you use Graphene. All possible technical improvements aside this is a very big risk. He claimed he would step back after the video released, then called that a lie and continued with everything.
Calyx seems to be the best alternative right now without such a risk factor.
At the time, Rossmann was mainly using GOS, but due to what he perceived as hostile behavior from GOS toward him through their communication, he opted to stop using GOS (at least on his main device, as he claims).
His rationale was that the behavior of said lead developer was not "rational" and "scary", and since the developer has not only edit access to GOS code but also update publishing infrastructure, Rossmann's data or himself could be targeted through malicious code pushed via an update, for example. While GOS is opensource and malicious code or exploits could be detected by the community, he himself did not have confidence to audit the source code to make sure it was safe, hence his decision to stop using.
By risk factor, I think the grandparent suggests that something similar could happen to someone else using GOS, the risk factor being essentially at the mercy of GOS developer, would they wish to harm said user.
if (user is rossmann) {
// do bad things
makes me think who is paranoid here.