It's not petty, there is clear confusion in the community between prestodb and the fork called prestosql, which also continued to call itself the "official presto" all this time.

Forks like this should really use a different name from the outset when the existing project is still alive with a large user base.

The trademark belongs to the Linux Foundation as far as I can tell (from the blog). The trademark being registered is standard open source protection move to stop other projects creating confusion with your open source project.

Facebook's involement here is that they funded the original development and then donated the project to the Linux Foundation.

The scummy part forking a project and creating a name that is clearly designed to make the fork to look like the original project. If Facebook did what they did when they named their porject the community would be up in arms about it.