At the time, in the beginning, it seemed too obvious.
The Novels outted an unknown as Future Guy, but here's turd of a question... Would pocketbooks have shot down "Archer is Future Guy" or would they really have not cared since Enterprise was dead and buried and there was no new canon to worry about.
Furthermore now that Future Guy has been outed does the continuing cast of Enterprise in the Novels have the class to pretend that they don't know who Future Guy is when they meet past version of him in their future so that they dion't fuck up their own personal timelines?
General Hammond from Stargate pretended since 1969 that he didn't know what a Stargate was, which must have been more complex after he was put in charge of the SGC.
It's merely a question of politeness.
Oddly in Marvel a new character turned up called Kid Immortus who has a really fucked up timeline where he attends cross time conventions of himself to discuss policy and recent campaigns... Never mind.