I don't think the dad's wording is accurate, but I also wouldn't say MC is satisfied. If he was, we wouldn't have much of a story. The main pair enjoy being alone, but that doesn't mean they're never lonely. They're not making an effort to forge connections, to have even one close friend. So it's like the dad is pointing out his son isn't working on himself? He's still a wimp, no confidence blah blah. Can't make friends even if he wants to. And has simply accepted this, seemingly... Uhh or that's my take anyway. I want to be careful so as not to imply that people who like being alone are lacking somehow, and I hope and believe this comic isn't saying that either. Butyeah.