To be clear, this measure vis-à-vis the financial institution doesn't remove joint and several liability for the financial institution where business is being carried on in the tax-free savings account. Rather, it limits the joint and several liability of the financial institution for tax arising as a consequence of carrying on a business in a tax-free savings account to the amount of property in the tax-free savings account. In addition, there would be the amount associated with distributions of property from the tax-free savings account after the financial institution received the notice of assessment or the act against trustee and became aware of the tax liability. They couldn't avoid this joint and several liability just by distributing all the money out of the TFSA. It doesn't eliminate the liability with respect to the trustee of the TFSA. Rather, it provides a cap on the liability, and that cap is equal to the assets in the tax-free savings account. That's where one would expect the collections to be from the TFSA itself.
The second component is that it extends it to the TFSA holder, who is in the best position to know if they are carrying on business or not. It's not the elimination of joint and several liability. Rather, it's putting a cap on it, based on the value of the assets they have as trustee.