SHUT UP EDDINGTON! NOBODY LIKES YOU!
Okay, I admit Vendome came after, but still, it's not like ops/security/engineering people have never become captain. Plus, come on. Vendome's face was just begging to be memed.
The main example I can think of from canonically before this moment is Uhura, though everyone was wearing red uniforms at the time.
Worf worked in security and got to be first officer of the Enterprise. After that became Strategic Operations Officer on DS9, which is command even though it's still ops related. As a bonus he became first officer on the Defiant as well.
Counter argument: Geordi’s in a gold admiral’s uniform.
Didn't he become a Commodore, not an Admiral?
A commodore is a one star flag officer. Commodore, rear admiral, vice admiral, admiral.
