Contributor != committer. Great projects need both people who are sticklers for process and code quality, and people who can focus on push the boundaries of what is possible while knowing that others have their backs on process. It appears the author is on the boundary pushing side, and that doesn’t diminish his contribution in the slightest.
Being a contributor and having commit permissions are technically different things. Dimitri is listed as a contributor on the appropriate wiki page https://www.postgresql.org/community/contributors/
Being a contributor and having commit access are orthogonal.
FWIW he is listed here
https://twitter.com/tapoueh
> PostgreSQL Major Contributor (CREATE EXTENSION, Event Triggers), pgloader, el-get
This is a very bold lie to put on your Twitter, I'm going to go ahead and assume he's not one and the postgres wiki needs to be updated
[EDIT] - I stand corrected, everyone (but me) is right -- He is a contributor, not a committer to the Postgres project, and considered at the very least a major/notable contributor. No one stated that he was a committer but the comment above clarifying that he's not one is correct.