To me you should read Google's guidelines as you would a sign on someone else's property.
"We reserve the right to refuse admission if..."
And let's face it, the guidelines are generic, easily defensible and, frankly, rather bland. The whole point of the affiliate line is that it includes "sufficient value". It's not possible to turn that into a black and white test of whether a practice is OK or not. But let's face it - we all know the sorts of sites this is calling out, and it isn't controversial cases. The sneaky redirect isn't sneaky because of the redirect - it's because of the context!
The guidelines are the sign to hold up to say "this is why you didn't get in".
But as others have pointed out, a change in the guidelines is interesting. Google want to be able to hold up the sign that says why you weren't admitted, and if they change the guidelines, they are expecting to be doing this to some different people.