I think there are logical explanations for both;
Imma's funeral
Traditionally, funerals are considered 'safe' from hostilities. And true to form, no one died at the funeral. Ciro realized that a certain element was missing, which set off his alarms, and lo and behold it was that element that ambushed people _after_ the funeral. So he was actually entirely correct that the funeral was safe, and also entirely correct that he needed to get a jump on what was going to happen after.
Genny
There is a great scene that described the entire Genny/Ciro arc for me, when Genny mentions his hometown (well after his issues with Ciro reached a boiling point) and says 'his brother' is there. Genny and Ciro are, for all intents and purposes, brothers. Even more so after Genny's return from being a hostage at the jungle camp; the new Genny is not just a brother but a potential equal. There is a really bad analysis floating around about why Genny doesnt kill Ciro in the hotel room. The party line being bandied about is 'oh leaving Ciro in play means Genny can use Ciro to check his father' or some similar shit. Thats basically retarded. Genny uses that as an _excuse_ not to kill Ciro, but its affection that keeps Ciro alive more than anything else. And Ciro's refusal to land a kill shot in Genny is rooted in entirely the same affection.
Not to say its entirely one thing and not the other of course. What I love most about this show is the ambiguity. Motives are multi layered and flexible and nuanced. American films never, ever do that right. Its so rare, its the difference between art and Hollywood trash, and its why this show feels so ulta fucking real.