I say no to known noxious fish, however if it is fish that you know could not survive due climate conditions I say good luck to those who keep them provided they never release them.Here in Queensland,Australia we can't import a lot of species but we can keep , sell and breed most fish that are already in the state as long as they are not on the noxious species list.Remember that most species would be able to survive with our climate yet states like South Australia have very strict rules and don't allow most species taken for granted here in Queensland even though a lot of the species banned could not survive with the climate of that area.
Qld= non strict regulations yet most species could survive if released.
SA=strict regulations yet most banned fish wouldn't survive.
Sometimes I think they have it backwards.
It also depends on the person keeping such specimens.
All in all I would rather see 100 responsible fish keepers , keeping illegal fish(provided they are not noxious fish) than 1 irresponsible $%ker buying what is not illegal at the local pet shop ,watch it out grow their tank and then release the fish.