I wouldn't say it's implied at all, I think you're inferring quite a lot from very little in the text. I don't imagine Space Marines ever gettin "crestfallen" about things like that, and the background certainly doesn't say anything along those lines. Get annoyed with the background for what it says, not what you think it's suggesting.
I can't imagine them doing so either, so that's where it becomes problematical for me. As far as me being wrong about what it seems to say, anyone's reading is an interpretation. It's not as though I'm the only one inferring meaning. Here is my train of thought on the matter:
Premise 1: Most Marines wish that they could be Ultramarines.
Premise 2: They can never be Ultramarines.
Premise 3: Wanting to be something that one knows one never can usually if not inevitably leads to frustration.
Conclusion: Therefore, non-Ultra- Marines are to some extent likely to be emotionally distraught about not being Ultramarines. (Marines may be stoic but they still essentially experience normal human emotional reactions to everything but the horrors of war, as far as I can tell from the fiction.)
Now I fully understand and accept that this may be different from the way you interpreted it, and I do not think my interpretation is somehow superior. However, I also dare say it isn't outlandish or crazy, and many other readers have independently come to the same conclusion, as demonstrated by this thread. Dismissing that as "deciding to get pissed" is a bit disrespectful, honestly. Not all of us are mad about it, we just don't like it, and anyway nerds have some prerogative to nerdrage every once in a while right?
You've just made that up, he isn't doing anything even close to that
I think Faye was saying that when he makes claims about how all non-Ultramarine Codex chapters feel about Ultramarines, it does kind of feel like he's telling you how your homemade Codex chapter is supposed to see them. If he had just listed the views of the specific chapters, i.e. Imperial Fists, Raven Guard, Salamanders, etc. that would be one thing, but he painted with a bit broader a brush than that. From Matt Ward's writing it seems that if you made a chapter who didn't much care for the Ultras you'd be violating canon. Personally I don't mind violating canon, but I'd also rather not, all else being equal.
And yet there are many reasons that other chapters might not care for the Ultras, including the fact that their mini-empire and massive leadership role are slightly hypocritical given that the purpose of the Codex Astartes was to limit the power of the Marines, along with potential suspicion about them being absent during the Siege of Terra. (I know they had a decent excuse, but not everyone in-universe knows or believes that certainly.)