Read it again. He's using incitement to violence as a consequence to to be avoided, not as a driving factor.

for it may easily turn out that they are not prepared to meet us on the level of rational argument, but begin by denouncing all argument; they may forbid their followers to listen to rational argument, because it is deceptive, and teach them to answer arguments by the use of their fists or pistols.

He goes on:

we should consider incitement to intolerance and persecution as criminal, in the same way as we should consider incitement to murder, or to kidnapping, or to the revival of the slave trade, as criminal.

He was writing at the end of WW2. He was saying it would have been fine to stop the Nazis at the start, before they were inciting violence because they couldn't be reasoned with.
It's clear you don't agree with his position , and that's okay. You can just disagree with him.