The 'sentiment' of this thread was a discussion about morals, and the peaceful resolution of what they are fighting about.
How a racist comment, whatever the motive, aids that discussion is highly questionable.

That book sounds, on the face of it, vile. That said I am not sure too many of the other side are going around and (idiotically) glorifying acts that they committed that were surely as horrific.

Either way, 'slit white throats' is not a justifiable or constructive comment at all. If that is what he truly thinks it should be kept to himself.
Would be interested to see 'slit all the brown throats' comment from a similar cretin to Mr Robot, and see how that 'sentiment' is defended.

Hint; it wouldn't be.