I'm a bit confused. If you're going to pick over minutiae, you probably need to stick to the generally accepted rules of what canon actually is. It's not included the FASA or Franz Joseph stuff since at least 1987 when TNG came along and invalidated virtually all of it.
So, you need to be a bit more creative and think why Morrow would have said something which appears wrong.
- He made a mistake. To err is human. Even for a highly intelligent and trained admiral.
- He is correct.
If it's 1, then that's the end of that. If it's 2, what do you think could be the explanation? One that immediately comes to mind is the difference between Pike's ship and Kirk's. Pike's seems smaller. It's got that big bridge module, and only 200 crew. What if they are different ships? Perhaps it was after WNMHGB, and she suffered irreparable damage? At the very least, there were physical changes, and the engines were upgraded to dilithium power over lithium. What if, offscreen, Kirk was given a brand new ship which inherited the name and numbers of Pike's Enterprise? It could have been the Enterprise-A without the A. Morrow would be perfectly correct, and the differences between the pilot and the series ships are explained.