As you know, I wrote that. The problem is that browsers do not allow you to bind them to the VPN interface in the way that torrent clients do.
So in addition to restoring the non-VPN interface as the default gateway, when I want to use the VPN for browsing, I start SQUID HTTP proxy (from Cygwin on Windows), and bind that to the VPN interface, Then I have a Firefox profile set up to use SQUID. So I do not have to put the VPN back as the default gateway while I browse over the VPN.
I have not documented this there, as I have never seen anyone show an interest in this. I can provide the script I use to run SQUID if anyone wants to see it.
Of course, you still have to start the VPN and now also SQUID with this approach. So this is probably not going to appeal.