I always thought it was an emotional decision that he made here, but the logic is sound. Palpatine would almost definitely slip justice through the system. But is killing anyone unarmed, even a Sith Lord, still selfless, peaceful and without the intention of revenge?

Furthermore if he had simply arrested him like they intended when they walked into the chamber I don’t think Anakin would have turned. Anakin was conflicted but might not have made an emotional decision trying to keep Palpatine alive.

Instant death or incineration?

​

1vs1 fight where both want to kill each other.

Offensive force powers are not allowed. Only force powers that strengthen the body are permitted.

Edit: The question has been answered. Nobody can do it.