Rough design:

Ability: Units next to gentleman looses abilities. NOTE, it doesnt effect all of enemy units, only ones that are next to gentleman race.
Story: True gentleman doesn't rely on cheap (or expensive) tricks. Fight like a gentleman, die like a gentleman.
Idea: Now that everyone is thinking of race with new abilities why not race without abilities. Though races with spawn bonus would have abit benefit as it would be unfair to disable it as it would effect all of units