Since the beginning of One Piece's Egghead Arc, the Seraphim have been causing a lot of trouble for the Straw Hat Pirates. Aside from how difficult it can be to fight them, they frequently switch sides depending on who has the most power. They are currently carrying out the traitor Vegapunk's orders to kill everyone.
If necessary, the Straw Hats could probably wipe out the Seraphim, but they might not want to. The Seraphim possess sentience, unlike the majority of Pacifists they have previously battled. The consequences of destroying them could be the same as those of taking a life.
The Seraphim: How Human Are They?
At first, there were only subtle signs that the Seraphim had their own thoughts and feelings. They would have mild changes to their expressions and even produced word bubbles with ellipses to suggest thought. Both of these things were far from the capabilities of the cold, unthinking machines that the other Pacifistas seemed to be.
Of course, there are some more concrete signs that the Seraphim have humanity. In Chapter 1070, "The Strongest Form of Humanity," S-Snake was shown getting flustered and defensive when Jimbei paid her a compliment. In Chapter 1073, "Miss Buckingham Stussy," S-Hawk being pushed back by Zoro caused him to show an intense face complete with forehead veins and sweat drops; if that scene isn't an ideal metaphor for the moral dilemma surrounding the Seraphim, nothing is. Zoro even noted that S-Hawk seemed more human than the person he was modeled after. Even if they move and act like machines most of the time, they are still alive deep down.
As human as the Seraphim are, however, leaving them alive might be too dangerous. Even if the Straw Hats manage to find the traitor among the Vegapunks and get the Seraphim back under control, St. Jaygarcia Saturn could put them all under his absolute control once he arrives on Egghead. The Straw Hats could stop them again by knocking out Saturn so control defaults to their ally, Stussy, but that would require them to get through Admiral Kizaru and all the warships he's bringing to Egghead; this would be while the Seraphim are on the attack. At that point, trying to stop the Seraphim without causing too much harm to them could become more trouble than it's worth.
Could the Seraphim Become Allies in the Egghead Arc?
Despite this, many fans believe Kizaru and the Straw Hats will face off to end the Egghead Arc. They might as well target Saturn while they're at it if that occurs. By doing so, they could defeat the opponents they would eventually have to battle and win the Seraphim back to their side.
The Straw Hats would probably aim to knock the Seraphim out rather than destroy them if it came to a full-fledged fight. In the unlikely event that these killing machines ever find themselves on their side, whether it be on Egghead or somewhere else, they might even try to be relatively gentle about it. Despite being murderous machines, they are entitled to life just like any other sentient being.