The Issue with Characters not sharing Cash Shop Inv?

I don't get it. You mean that once an adventurer puts the NX item into his personal inventory, he can transfer it back to the CS inventory, and have another adventurer collect the item?

Yes, that is what he said. If you own an "80s Pullover" you can wear it on one character until it expires, or share it among all other Adventurers on the account by putting it in and taking it out of the Cash Shop Inventory...