The question is, when can the fist player decide the passive effects order of resolution : for any passive effects or just for conflicting effects? And by the way, what are conflicting effects?
For a start, the FAQ says the following p.15:
"Passive Effects Conflict
If two passive effects are triggered at the same
time, the first player always chooses the order
in which these effects are resolved."
And this at p.17 :
"Remember that if two passive
abilities are triggered at the same time, their
order of resolution is determined by the first
player."
And this at p.15 :
"Lasting Effects Conflict
Even if not triggered at the same time,
multiple Lasting Effects may affect the
same card at the same time."
Let's assume the First player decide the order of resolution only for conflicting effects, and others resolves simultaneously when triggered.
One possibility is that conficting effects means that 2 effects cannot resolve at the same time because they kind of contradict each other : for example a character who would be killed and discarded at the same time. Following this definition, other effects that can live with eachother would resolve simultaneously. For instance, I can draw a card with Golden Tooth Mine and discard a character with Threat from the North. But in this case, timing become confusing. For example, which effect can I cancel first? Depending on if I cancel one or the other, my opponent might have different Responses. So how do we choose : rolling a dice? or maybe the first player should choose… and the 2 effects we thought not conflicting are indeed conflicting, and the only reason is that they are triggerred at the same time.
So, a definition of conflicting effects should be that they affect the game at the same time or are triggerred at the same time, which is very consistent with the FAQ wording p.15.
"Lasting Effects Conflict
Even if not triggered at the same time,
multiple Lasting Effects may affect the
same card at the same time."
And as a conclusion I'd say that the first player Always decide the order of resolution of passive effects, because when they trigger at the same time they are conflicting by definition.
And yes, there IS a nasty combo behind this :-D