The thing is, if mafia correctly guesses president at night, they're rewarded with a win. If they do it during the day during prez math, they can still lose if president decides to lynch them.
Let's follow the strat. GS outs and gets mislynched and mafia does nothing D1 spy just contacts sniper.
1. If spy NK's and town decides to force NL D2, sniper can blitz as he has a gun and the day won't be hammered until he decides what to do with the gun. 2. If both mafia yolo kill between 3 bombs and the president, they have exactly 50% to win the game, so it's not extremely townsided if mafia is prevented from getting reads. 3. If spy yolo-kills and it turns out to be 75% chance of hitting bomb, the sniper may stall the gun. 3a. In the worst for mafia case, sniper will be obvious scumtelling which ends up with sniper yolo-shooting, which gives results in 2. 3b. Town will have to give reads before scumreading sniper, therefore sniper gets president reads. If they decide to random lynch without giving reads, it's 33% chance of finding the sniper which results in 2. or even majority chance of mislynching town which improves mafia's chance of win over given 50%. 3c. If sniper avoids getting lynched over 2 remaining bombs, the sniper immediately wins the game.