I see where you're coming from, but having to press back twice quickly to get back to the page I actually came from is very annoying. It's essentially impossible on mobile.
Perhaps browsers should disable redirection on pages that have been reached via the back button? That could add a lot of complexity.
In Firefox for Android, I can press and hold on the Back button in the '…' menu (not Android's Back button) to show the current Rab's history as a list. By touching an old history entry, I can navigate directly to it, skipping any redirects.
Could be a legal issue. If they have a legal requirement to not serve ads in the UK it's good to have a clean separation where they can see if the redirect is broken.