With the current implementation of the VPN kill switch, correct me if I am wrong. When you enable block non VPN traffic, it blocks all traffic globally on the router even if you have VPN policies configured on the router to enable certain devices thought the VPN.
If this is the case, there should be a toggle added to the VPN policies page where the user can do a per connection kill switch for the client device or VLAN or whatever policy you have configured. Instead of just blocking all trafficr globally.