ADA Business BRIEF: Service Animals
Service animals are animals that are individually trained to perform tasks for people with disabilities such as guiding people who are blind, alerting people who are deaf, pulling wheelchairs, alerting and protecting a person who is having a seizure, or performing other special tasks.

Yes they do need to do tasks. THe IAADP is a private organization that has created its own standards independent of the Federal and State Government requirements. Their standaards, while admirable really have no legal standing. I am a rehab professional so I deal this all the time.

In order to qualify as service animal it has to "perfom a task". While the cat is surely helping his owner cope it can not be considered a service animal unless it has been trained to do something to assist with the disability. If it is just being a comfort, then it is an emotional support animal and as as such is excluded from the protection of the ADA.