Yes, I don't think it's about being mono or poly, but about being considerate. I made sure to use some examples that had nothing to do with polyamory in order to illustrate that. For instance, where you live is your own decision in the end. However, informing a partner you're moving away in two days, without involving them in the decision at all, isn't very considerate, especially if they live with you. It will affect them so they should be made part of the decision.
Of course if they refuse to talk until you absolutely have to make the decision on your own, it's another story >.>
Anyways, I think some people have suffered from having to live mono for years, and they feel it's only fair that they get to decide now since their partner did for so long and they were miserable. The issue here is one from another thread: if all this time you never told your partner you were miserable, then you can't hold them responsible for it.
It can be hard to see both (or all) sides of an issue, but yes, everyone needs to. Now, in your examples, the only one I disagree with is the sex one, as I don't see how someone could force themselves to have sex with someone they don't want to, or be called inconsiderate. Nobody ever owes anyone else sex.
This being said, if the person says "So and so has decided I shouldn't have sex with you, and although I would like to, well I've got to honor their decision" then yes, it's the definition we've mentioned above. It doesn't really matter whether so and so is an older or recent partner, or whether so and so is mono or poly.
If a decision involves you, you should be involved in making it.
If a decision doesn't directly involve you but affects you, you should be able to give your opinion and input before the decision is eventually made (by those actually involved).
If a decision doesn't involve you, you shouldn't be the one making it, although you might be given the opportunity to present your opinion.
How long you've been together or how mono you are isn't relevant. It's about treating others with respect, and working together when it gets tough rather than just telling someone to go away or shut up because they're making the situation less convenient.