This is precisely what happened, its “legal” but unsupported, blizzard won’t ban it for some reason when they absolutely should, considering that you can legally purchase gold through tokens on other versions of the game, not to mention that you have no way to verify if the person you are legally trading with illegally gathered the gold. They ninja updated the ToS about 6 months ago after they banned an absolute ton of people on SoD for the same thing.
Its extremely customer unfriendly, basically they cannot tell if you bought gold or not, they’ll just shoot you with the same bullet they’d use for an actual gold buyer, its a failure of both their own systems and their own janky rules being passed down to the customer and told its their fault.
Don’t expect sympathy on these forums though, there are an army of people who will support a company banning people for not knowingly breaking any rules because they have some weird vigilantism against people who they believe are “doing wrong” by transferring gold between games legally