The tax-free savings account is a multi-purpose vehicle. You can save in your tax-free savings account and if you want to buy a car and you have enough money in your account, you can withdraw it. You can use it to buy your home. But certainly it can also be used for retirement income. It's a multi-purpose available tax-free savings account, so it can be used for that as well.
The other thing that's quite a benefit of the tax-free savings account is that on the money put into a tax-free savings account, the earnings are accumulated tax-free. But when you withdraw the amount from your tax-free savings account it won't affect your GIS benefits or any other benefits upon withdrawal. You pay the tax up front and then you don't pay the tax after.