No Mutants Allowed

What statement? Are you referring to Yes Man's passive aggressiveness?

Yes Man has a rather ominous line in his ending where he refers to being more assertive and not being told what to do anymore. It's left vague as to what that means and considering he says he'll be offline for a time and the slides deal only with the immediate aftermath, it's a bit sinister

Sawyer after NV said that all it meant was Yes Man would only take orders from the Courier, but he later retracted that statement saying he shouldn't have spoke for the other writers and his word should not be taken as gospel at all

Which restores the ambiguity of the line

It was there to asure the player that Yes man wouldn't be duped by some other person, but I think any good writer realizes that leaving it vague and up for it to be itnerpreted in an ominous direction is much more interesting for the setting.

Honestly, just tell Yes Man that he still has to follow orders from you.

Problem solved.

Remember that that is the loophole Emily Ortal left in his coding, he is simply programmed to help whoever asks but doesn't discriminate who. My head canon is that after taking over the Lucky 38, Yes Man probably got mixed with the brain scan of House and adopted some of his traits, which if we would ever get an actual sequel to Fallout could present an interesting opportunity for a new faction.