I beg to differ.

When Michael gets back to the compound he finds Teresa Hagen neglected "waiting in a lobby." Sonny didn't even think about her, and Michael had to take up the slack.

Inside the office, Sonny asks for Tom's advice about what to do if Vito dies, and when Tom tells him the harsh truth, Sonny replies by saying ,"That's easy for you to say, he's not your father."

Next he tries to enlist Mike in the war and Tom has to remind him that Mike should not be too directly involved.

Then he orders Paulie's death in front of Tom, Mike, Tessio and Clemenza...talk about not using buffas....

The next day he insults Clemenza for teaching Michael how to cook pasta by telling him to cut the crap, and then he asks in front of everyone in the kitchen about Paulie's fate.

It is in that same scene where Michael says he is going to the city to visit Pop in the hospital, so that visit is not an afterthougt. He was going there for a reason.