Would the zoo dismiss stereotypic behaviors in autistic children as "bad habits"? I doubt it somehow.
While it is unarguable that bad habits can be both difficult to stop and, like smoking, can threaten our health, describing a recognized mental health issue as a "bad habit" is both misleading and offensive; particularly when the true explanation behind stereotypical behavior in animals in zoos has been accepted, even by the zoo industry, for many years.
Stereotypical behavior is caused by captivity. It is zoos themselves that cause stereotypical behaviors.
The wording of the sign stuck with me for the five hours I was at the zoo and, before I left, I went back to the elephant enclosure, which was no longer surrounded by people. For ten minutes, I watched a female elephant sway backwards and forwards from side to side. You can see her below:
Elephant, Chester Zoo, June 2014