Step 5 is problematic because when people won't put www.4chan.com but will type 4chan into address bar (90% users are doing exactly that) it will trigger search and will easily find some AMPed URL, URL shortener or subdomain to click on.

HMG can compel Google not to offer AMPed 4chan in the UK, and can compel ISPs to block mirrors in DNS and by IP. URL shorteners are just a client-side indirection and won't circumvent a block.

There's really nothing that they can realistically do about VPNs, however.