Who says? If the instructions on the app you're filling out state that, sure follow their guidance.

But in general, no. CP has a specific meaning, and in most cases it's defined in the regs. Any mil CO will get full credit for command from any airline (well any airline worth working for), don't need to risk appearing to game the system. Possible, likely, that nobody would care but also posible someone might take offense (say a civilian who really was a CP).