No GrapheneOS is not just calling them out on lack of security.
It's apparently from their discord, so it took me a while to find it again.
It's not about the personality of it's directors, it's about it's effect on the (alternative) Android ecosystem as a whole, which is not just about security but also privacy and user control.
Even with regards to security, their choice of limiting devices apparently makes their users targets for extra scrutiny and harassment. That does have actual implications for people whose threat model includes authorities unless they already are guaranteed to be targets.