Maybe they didn't anticipate that a site that rigorously polices (for example) breast-feeding pictures and race hate material wouldn't rigorously police "rape a bitch" image macros.
They have discovered that having their ads next to this sort of content is not what they signed up for, after all, and are planning to unsign up for this stuff. Companies change their minds all the time about where they advertise - advertising on a service isn't some sort of lifetime promise.
Maybe they didn't anticipate that a site that rigorously polices (for example) breast-feeding pictures and race hate material wouldn't rigorously police "rape a bitch" image macros.
They have discovered that having their ads next to this sort of content is not what they signed up for, after all, and are planning to unsign up for this stuff. Companies change their minds all the time about where they advertise - advertising on a service isn't some sort of lifetime promise.