This does raise an interesting dilemma for GB producers and shippers : stock held in w/h for shipment is now vulnerable to almsot total loss froma few casts : stock being shipped is already vulnerable to skirmish loss : now it is vulnerable to loss via punitive voodoo casts, which can also act as a 'spy' to establish if a given fleet is carrying GB for a subsequent skirmish : that the card needed is common and has a low use cost is also a factor.
My own feeling is to say 'sod it' and not bother shipping again, to reduce any stockpiles I may have held against a rainy day (or price spike) and thus consider that whole element of the game to have held promise but proved to be no better than common or garden trading : much the way fishing held great promise but never delivered : i,.e the specialist fishing vessel.
How this may impact on the planned expansion of GB requirements is maybe moot : I am just one GB producer : I cant say how others may react : we have invested vast sums in the enterprise, after all and most will just have to make the best of it, make what return they can and maybe regret falling for the hype.
If each 'improvement' will always be reined back to be no better than trading, quite why are we to feel driven to invest in it?