I feel like Jim’s the type of Captain who would one day be struck by the brilliant realization that crew members with dual specializations could have their own uniforms colors:
Dual Command and Engineering or Security would be Orange
Dual Command and Science would be Green
Dual Science and Engineering or Security would be Purple
It’d make a beautiful rainbow
And he’d have to talked down by the rest of the crew including Spock who would secretly agree with logic of Jim’s stance while arguing against it on technical grounds (and because it’s against the rules).