Essentially you're saying "it's not consistent with another rule" and it "doesn't make sense."
You can't play both sides of the coin here...
I sure can. I'm not claiming to be following the letter of the law, I'm saying that's my personal ruling. I don't care if it's in the rulebooks or if its a house rule.
The real reason is because on this issue there
is an actual inconsistency, not just something you find that doesn't make sense to you. The situation is like this: you want to attack something that, when you draw your lines from your best corner, has superior cover according to this: "If three or four of those lines are blocked but you have line of effect, the target has superior cover," because there is another enemy or group of enemies in the way. It doesn't explicitly say that for the three or four line case that creatures should be taken into account, but there is an implication. The bullet directly above that says "When you make a ranged attack against an enemy and other enemies are in the way, your target has cover." The rules say that when making this ranged attack, the defender will have cover and superior cover. That is internally inconsistent.
If you decide that the "Creatures and Cover" section only applies to ranged attacks and "Determining Cover" applies to everything else: when you shoot an arrow, the target will have cover, but when determining stealth, or anything else besides attacking, that target will have superior cover. If that was the intention, it doesn't make any intuitive sense. Is this your argument? In a sense, yes, but I disagreed from the beginning that hiding behind allies is realistic or intuitive or made sense. I didn't disagree with your method, just your substance. Do you think that ranged attacks only having cover but sight having superior cover makes sense?
To add to that reasoning, the stealth errata makes it clear to me that creatures aren't meant to provide superior cover. Because like you said the situation where you suddenly lose stealth is ridiculous. But it's not ridiculous if you never could have stealth in the first place from creature cover alone. I feel that this ruling actually does give the designers credit, because the ridiculous situation you point out actually doesn't occur, and there are no leaps such as the one that you make that you only risk becoming unhidden when 'conditions change,' which as you can tell from the general board response, is unprecedented in the actual rules.
This doesn't change anything we were talking about before, however. The previous discussion was whether or not you could maintain stealth by only having an ally/allies giving you cover, which is a clear "NO" from the stealth errata, no matter if those allies were precariously used to give you stealth in the first place, or if you stealthed over from behind a wall, or whatever. You simply cannot maintain stealth from the cover an ally alone, by the rules. There is no inconsistency on this point.
As far I can tell, I have satisfied the rulebook "to the letter," so please tell me, does it or not?
I don't believe allies can create superior cover, so no, it does not. The next guy will say yes, it does. This part of the rule is up to interpretation. See above. Whether you can maintain stealth behind an ally is most certainly not, if the response here on this board is any indication to you of that.
So, to be clear, I'm not playing two sides of the same coin. I'm playing tails on one coin and heads on another. Actually, I don't like this analogy. The point is, these are entirely different issues (maintaining cover behind allies and whether allies provide superior cover), and I feel that my ruling wraps things up nicely.
