Yes a single cold tolerant snakehead species were responsible for the snakehead ban. Funny thing is that there are other snakeheads have been in United States for over 20 years with no issues. That said, 99% of snakehead species cannot survive most areas of United States.
You are correct, but the problem is the fish and wildlife inspectors can't be expected to be able to identify every fish. So, they banned them all. We are lucky that they don't ban the aros from Australia, as at a glance a juvie could be mistaken for the formosus.