I am aware that there are multiple ways to get off the Source Collars, and have used them, but even so, this appears to be a bug in Nebora's dialog that should be addressed.
As to the trading, weight-based strategy puzzles (which have been common in RPGs like this) are trivial for players to overcome (this was especially true for me when dealing with the Gargoyle's Maze). I say it is a bug and not a "feature" because inventory swapping across maps makes item weights and inventory carrying capacities non-essential and somewhat pointless...yet, developers continue to build with weight in mind. So certainly, this must be an oversight. But, I do take advantage of this at times, if only for personal convenience in my single player game; for others who do the same and want to see this functionality kept, it may be possible for developers to simply make it a "togglable option" on any campaign.
On that note, I should add that having two party members with access to Teleportation (Aerotheurge I) makes overcoming almost any locked gate trivial as well. It might be worth having some kind of "Teleportation Dampening Field" feature enforced on certain puzzle areas (like the Gargoyle's Maze, again) so that a group is encouraged to at least attempt the challenge.