I'm very sure that's not the case according to all leaks and information I got. Why should they use 14 CUs when they know the system will ship with 12 CUs?
Why would they toy with the idea of using all 14 CU's if they had no chance of the console running with 14 CU's?
Chances are 12 CU's was the safe bet just in case the yields are not so good & 14 CU's was the dream number if the yields was good enough to take the hit.