When saying "If you make a commitment to another person, you should keep it." I see you as being in agreement with the post I just read.
If you recognize that this is a real problem, you can take steps to fix it. Things like shifting your schedule or regulating blue light. Not just "don't be lazy" or "get off Reddit", that sort of attitude doesn't help.
The original referenced material doesn't talk about making excuses. He talks about managing a real physical condition so that you don't miss meetings and don't have to make excuses. It's about understanding that having that condition doesn't make you lazy or a lesser person.
The author's point is that many people with this "disorder" continue to make commitments they cannot keep. It is Jason Freedman who says "The one who can’t seem to consistently set the alarm clock for A.M. and not P.M. I know how it feels to be the undependable one."
If you are consciously aware of this, yet continue to make these commitments - then the author I believe argues you are a "lazy", "sissy."
I don't feel guilty for over-sleeping. I've worked out a life for myself where people don't care that I sleep until 11:00. I simply don't schedule meetings or appointments for the morning, or if there's absolutely one that can't be avoided, I go to bed early and set an alarm clock to wake up for it.
It is not being a sissy to know your limitations and preferences and to work around them. If you make a commitment to another person, you should keep it. But nobody is forcing you to make that commitment in the first place. Is it really impossible to schedule that meeting in the afternoon, or to not have it at all?
It's not the OPs place to say what sort of sleep habits other people should or should not have. If he finds them annoying, fine: don't work with them.