Think being calm in the face of confrontation is in Vito's nature.

There is story in the novel about Vito working somewhere with Irish workers and them heaping ALL kinds of verbal abuse at him daily, and Vito pretending to not understand what they were saying and just calmly finishing his job.

I think his "management style" of never making a threat developed as he ascended in the underworld and dealt with others who were hot headed by nature or felt that making threats helped them achieve whatever they were trying to get done.

He saw the error of using such tactics,and being a businessman on top of everything, he always sought a way to RESOLVE issues or disputes in as constructive a manner as possible.

He might have arrived at the conclusion somewhere in his criminal life that it was his father's hot heat that lead to his demise, but he surely wasn't old enough at the time to understand that.