Won't the wrong design just keep negative voltages from going into the resistors, vs keep them from going into the connector?
No Both drawings are accurate, one (the first one) is a 5V bus adaption and the second one is a 3V3 buss. To use it on a 5V bus add the resistors from the first drawing or some just like them. Neither is wrong, just for different bus voltages and the first one shows how to convert the second.Helpful?
... im sure they wouldn't sell you something that'll blow up your arduino ...
... now for a 10 to 6 pin adapter
Not odd, It's Greed.