Trader Joe's probably wants to protect their brand in hopes of a future Canadian expansion.
There's no trademark devaluation. There's no copyright infringement. There's no patent infringement. This is straight up First Sale Doctrine stuff. And even if there was the above 3, SCOUTS ruled those rights are exhausted on sale recently.
This is directly an issue of "More Money = Better Legal Justice". And that should be very worrying.
Easiest way to fix this I think is to make it so that the plaintiff in these kinds of suits has to show real, actual damage: not to branding, not to "theoretical sales", not to "possible expansion", but actual and documented ill effects on their business resulting from the activity of the defendant, and more importantly make the award for such a case relative to that damage. That would shut down 90% of these cases overnight.
This is the most tried-and-true, reliable method of becoming rich in history. You buy something at full retail price, move it, and resell it at a higher full retail price.