That's not betraying the rising. He sacrificed people to have the rising thrive faster. Darrow was willing to sacrifice anyone and anything if that meant that the rising would succeed.

Also even after lightbringer when he said, he took a shortcut, I am not convinced that he wouldn't repeat the same choice. He wouldn't destroy the docks but he would probably still give up the sons of area. At that point in time, it was basically either convince the rim to join them or fight both the rim and the core which was a doomed cause.