Yes, that's because their allegation can be demonstrably proven to be untrue in some way or under pressure in court they admit it is. Whether Suarez said something nasty to Evra on Saturday, or vice versa, is something only they know unless something turns up positively proving the claim. As I say, in practice to negatively prove that claim would be nigh on impossible without a close up camera on Suarez's face the entire game and even then it would probably still be inconclusive.