• I disagree with one of their points

    Network firewalls can also be configured to deny inbound and outbound traffic to and from the physical interface. This remedy is problematic for two reasons: (1) a VPN user connecting to an untrusted network has no ability to control the firewall and (2) it opens the same side channel present with the Linux mitigation.

    Sure, they can’t control the network firewall, but why would you do that when you can change your local firewall? Set an iptables rule to drop all traffic going out the physical interface that isn’t destined for the VPN server. I’m 70% sure some vpn clients do this automatically.