I did catch that, but I see it as rather irrelevant to your position. Suppose he said he was needing to drive his grandmother to the hospital for lifesaving surgery on Sunday. That would just mean it was up to him to sort his priorities and act accordingly. You seem to be worried about his nephew needing time with his uncle. That is way outside of what is within your rightful province of things to worry about.

Here's a hard lesson life taught me. I used to want to intervene, if I saw someone being not treated well by someone else. This came up at work a few times. It would seem to me like some of my coworkers were ganging up against another coworker, who seemed not able to hold her own among them. I'd feel sorry for the person I saw as vulnerable, and I'd insert myself into what was going on. That didn't work out well. I learned that everyone has to stand their own ground in this world, and everyone has to fight their own battles. Coming to the defense of others can become a bad habit that you'll often get no thanks for. Sometimes it's the right thing to do, but often it's not.

When someone treats someone else inconsiderately, it's kind of a favor that they're doing. They are showing who they are and what they're about. That is valuable information to the person who is being imposed upon. Now they know what to expect from the person who showed them no consideration. They'll know better how to handle that person next time.