What’s the point of giving a choice if Offline (But still connected online) between the Bazaar and the Observatory? If this has already been answered, might someone do my a solid and point me to it? Is there an official answer?
What kind of answer? 
No, there is no point in choosing Merchants Guild in offline or solo.
Some skills nodes are also only useful for allies, and useless offline / solo. Yet you can still see them in the game, because it wouldn’t make sense to code a completely different game just for soloists. Just don’t pick them.
But by showing them, because most players don’t actually go online to check forums and stuff, tells players who might solo, as you know, they played Diablo 1 and 2, and those are single player first games, is effectively lying to them.
Just have a tooltip saying it do not choose if not playing full online. Or something.