That's part of it. The other part is knowing what he's done, or what he will do, and not telling other people that we know.
I told Emmeline that Sirius didn't get James killed, but couldn't bring myself to tell her why again. And I didn't tell Dorcas, either, and there she is chatting him up.
I've wanted to repair things with him, and he deserves a shot to try again. I think. I don't even know anymore. I don't know how much of him is really rotten and how much was manipulated and changed.