I guess you missed the bit where it says: "He received C$10.5 million and prime minister Stephen Harper formally apologized to Arar for Canada's role in his "terrible ordeal" .[9][10]"

Sure, money doesn't necessarily negate a wrong completely, but this case is a good example to illustrate that the rule of law is supreme.

Moreover, I think there is a massive difference between Alquaeda related suspicions, etc, and other activities. I think they are considered to be enemy soldiers, therefore different standards apply.

The ultimate point is, you shouldn't be scared from your own government. You live in a country where the rule of law reigns supreme and your freedom is protected by the constitution. No need to self-censor, or be paranoid.