Correction: GrapheneOS is concerned with their so called "Android security model" more than anything else, and where that security model gives guarantees to app developers and service providers that harms the user's security, they merrily side with the developer's security against the user, at best give some more or less questionable reasons why that unfortunately currently cannot be changed, and at worst insult you for suggesting anything else.

I would think that rooting is not counterproductive. In fact my personal security model requires root access.

1. I need to be able to monitor what's inside the memory and communications of every process running if I want to

2. I need to be able to pin a different root certificate, install a MITM SSL proxy and see what every app is sending about me, if I want to