How about C: We have a tight deadline. Why don't you approach this by doing x and y. After we're finished and have production code deployed, you can refactor i

How about C: We have a tight deadline. Why don't you approach this by doing x and y. After we're finished and have production code deployed, you can refactor into z. In the process of implementing x and y, the developer will soon learn that z is inferior. If he doesn't, you need to get rid of him because he's incapable of learning.