http://www.bbc.co.uk/news/science-environment-16791094I think it's a blessing in disguise.
Human activity has thoroughly disrupted many ecosystems. The biggest losers tend to be those at the top - large carnivores - being on the apex of the pyramid, any change anywhere else removes part of their foundation. (Conversely, those at the extreme bottom, such as microscopic organisms, mollusks, insects and small animals such as rodents, tend to be least affected).
The newcomer is very similar to the former resident. Cold-blooded. Impressive scales. Carnivorous. Amphibian. Stealthy.
It is unrealistic to think that Humpty Dumpty can be put back together again - that ecosystems can be returned to their original state. I firmly believe that the actual goal of environmentalism should be to adjust habitats to be stable and self-sustaining given the reality of ongoing human activity.
I also believe that the best way to do this is to make those habitats useful to humans while preserving them in a reasonably pristine and natural form, because doing so will make humans stakeholders in their continued survival. So I think that the emphasis should be not eradicating alien species, but instead, adjusting the ecosystem to accommodate them in a sustainable way. The very fact that these snakes have made their home there and are the subject of continued hunting yet endure demonstrates clearly they are a success. Balance has been achieved - the snakes are doing well for themselves, and people are keeping the snakes from devouring all the small animals. The very fact that the native crocs have a fighting chance - balance of power - is just perfect. Instead of there being one winner, there are now two.
An even better idea might be to displace the snakes with another, similar, species of snake that happens to be seriously endangered in its native habitat.
Unfortunately, most environmentalists as well as people generally hostile to the idea of environmentalism are far too narrow minded to accept such ideas. But I do believe that in about a thousand years, the degradation of the biosphere will cause people to adopt such ideas out of compulsion, and ecological engineering will become a necessary science.

In conclusion, I'm a ridiculous nerd, and should be run over by a cement mixer.