If I was looking for guidelines in interpersonal relationships, I would look first to Sha'arei T'shuva, M'silas Yesharim, Chafeitz Chaim, etc. I would not look in Hilchos Pesach; and I would obviously not even be glancing down at the footnotes.
If I were looking for how to treat a corpse with proper dignity, I'd probably go to Yoreh Dei'ah somewhere. (That's a lie; I'd call R' Fuerst; but bear with me, please.) I know it is important, though, because of a Rashi in Chumash; where he notes that even the kohein gadol on his way to do the avoda of Yom Kippur would be required to first take care of a meis mitzvah. That's astounding! As important as the avoda of the kohein gadol on Yom Kippur is for all of Klal Yisrael, it does not take precedence over the kavod due a simple Jew whose corpse is lingering unburied; no relative or friend close enough to take care of his last needs in this world, so distant from the community that even the chevra kadisha is unaware of his death.
Yet, these show up together in Hilchos Pesach. Not in the Mishna Brura, not in the Biur Halacha. In the Sha'ar HaTziyun; you know, the footnotes at the bottom, that often seem to be just a list of roshei teivos (random letters separated by "s and spaces). Actually, though, I have found oodles of amazing insights down there. It's really worth glancing down now and then.
The Mishna Brura in hilchos chameitz on erev Pesach after midday (443:1), the addresses the question of whether to bury a meis or eat first when there is a chance that after the burial you won't get back in time to eat your last Dunkin Donuts before the holiday. "C'mon," you are thinking, "so the grave digger doesn't get his donut! He'll make do with fish, eggs, meat, fruit, and vegetables, like the rest of us!" The Mishna Brura (sk 6) says that when time is short, it is better to eat before burying the meis. The Sha'ar HaTziyun (sk 9) explains that you are being awfully cavalier with another Jew's feelings. Who says he is going to be satisfied with that? Moreover, further notes the Sha'ar HaTziyun, if you do force him to work before eating, he'll rush through things and not exercise the extreme kavod due this Jew. Much better, the Sha'ar HaTziyun, to eat first, then deal with the burial in a proper and respectful manner.
The message is loud and clear; whenever someone says what they can and can't do, what does and doesn't bother them... you have no right to impose your own criteria for what should and shouldn't be a big deal, what he can and can't do. Not only do you have to respect his right to feel that way, you have to change your behaviour accordingly.