The father went to far when he tried to kill the baby, remember that this criminals have a sort of "code of honor", that's why
Nikolay could convince Kirill not to kill the baby. Yeah, the boss could have been sent to prison (or killed before), but since he broke the code nobody would help him anymore. Kirill would be the new boss, but if I am not wrong, Nikolay was the next on the line (Besides...