Sure, but deactivating victory conditions seems like cheating when not winning before 2050 is the challenge.
The challenge is winning a histographic victory with a small difference in score between you and the leading AI. There is no deception in turning off victory conditions. There is nothing inconsistent with playing for a small score difference in turning off victory conditions. There is no breaking of rules by turning off victory condition(s) ... after all, we're talking about a single player game here. There is no hack of the game's program by having victory conditions unchecked. If anything, the game's program *encourages* unchecking those victory conditions if you see fit. Since those checkboxes are upfront it also seems likely that it got expected by the game designer's that players uncheck them. If anything, players unchecking them probably falls within what the game designers intended for the game... unlike how in The Conquests (e. g. Rise of Rome), victory conditions are set for the human player before the game and are unchangeable.
Supposing that the AIs will build spaceship parts, is it
unfair to the AIs, since they will build spaceship parts? But, the AIs will irrigate tiles in the ancient ages in despotism and then never change those tiles for any purpose. Human players can and often do change improvements on tiles, something that the AIs cannot do. And human players often use suicide curraghs. AIs can't do that. And shortrushing. And pillaging of one's one resources for more upgrades. And prebuilding (not wonder cascading... prebuilding). And knowledge of the move order (though maybe the AI programming takes that into account someway, I don't know). And research patterns... AIs can't pick what tech to research based on a guess or conjecture of what other players will research. And pillaging of trade routes. And using "leave or declare" after buying something for gpt.
If turning off the space race victory is unfair, because the AIs won't adapt, aren't also all of those techniques, and others probably, also unfair?
Also, the human player always moves first which affects research, attack order, and building completion. Is that fair to the AIs? Might they call it a 'cheat' if they could talk?
I also think that the AIs are also incapable of cash-rushing. If so, is cash-rushing unfair?
The AIs also can't use the luxury slider, can they? Is using the luxury slider unfair?
Is the human player having a rate of 100% science unfair, if the AIs can't do that?