It's not my problem

Our day classes are on Easter Break now, and I've been teaching a morning intensive course the last week. I teach offsite on Tuesday mornings, and remember Young Secretary telling me last week that Incompetent Colleague would be teaching it today. After the class yesterday, I took the logbook to IC and started to explain to him what I had been doing with them, to assist him with his lesson preparation. As I started, he told me that he wasn't teaching it. I decided not to argue with him, and went to the office and told YS that she needs to find another teacher for it, as IC had said that he wasn't teaching it. She told me that he was. I thought about going back to the teachers' room and telling IC what YS had said, but changed my mind and put the log book back in the rack (after all, I don't handle scheduling). I then returned to the teachers' room and began preparing for my next class.

Here's how the conversation went after that...
IC: Did you get that straightened out?
MrT: No
IC: Why not?
MrT: I won't be here tomorrow morning when there turns out not to be a teacher for the intensive class, so why do I care what happens?
IC: Fair enough.

********************** Update **********************
It turns out that IC did end up teaching the class yesterday, and they told me today (Wednesday) that they disliked him and his lesson.