Do yourselves a big favour, and remember something. TOS has never, ever, EVER agreed with ANYTHING done on a later series. Examining previous episodes, I come to the conclusion that there are two distinct Star Trek timelines.
1. Gene Roddenburry (until season 4 TNG)
2. Post Roddenburry
Enterprise falls into the later category. Anything that Roddenburry ever said has been thrown out. Enterprise is the TOS of the second timeline. While this is far from anything official in terms of cannon, if you keep in mind that you must discuss the first half of TNG and all of TOS SEPERATELY from the rest of star trek, it really does work. Sad, but true.
Alexander