Most people get banned for a clearly stated reason and many people who post harassment material in the community even get given second chances if it becomes clear they just do this because they are misinformed instead of being malicious.

GrapheneOS does not make many posts on their social media timelines about other projects which other people think are competing in the same space as GrapheneOS. Most of their posts referring to other projects are in reply of posts from other people that tagged (@'ed) GrapheneOS in their post. GrapheneOS replies to these people to inform them. Like many companies and oranganisation do, it's okay to point out how your project differs from others.

Many projects that claim or think to compete with GrapheneOS make many claims regarding the security and privacy they would offer even if their appraoch actually is detrimental to security and privacy compared to the upstream projects (AOSP) they are based on. This mismarketing is a big problem, it makes sense that GrapheneOS points this out if people are tagging them in social media post while putting them in the same category as those other OSes.

You are also reverting the situation. The other projects started personal attacks and harassment first. GrapheneOS just replies to it. Defending yourself from harassment and bullying is not bullying. Don't blame the victim. Don't rever the roles.