Would it be beneficial to upgrade to a different modem, if that's an option?
The risk should not be too great if your WiFi password actually differs from the password you use to log into your Shaw account.
You would be trusting their machines to not do nasty things to your network. If you are sharing with the general public, I would definitely set up a separate access point. If this is an air BNB type thing, you probably want to restrict physical access to the device as well.