Greek scholars who have more than a superficial knowledge of the language would never use this argument. The first is in the genitive case, and the second is in the accusative case. A number of Christian apologists, such as Gleason Archer, have used this argument. But they are wrong. In this instance, the genitive case does not change the meaning of the word in any way.
Some verbs take their direct objects in more than just the accusative case.
This is explicitly true of akouo, which can take either the accusative or the genitive. If the apologists are right and the genitive cases does change the meaning, then this would create dozens of contradictions elsewhere in the New Testament where such flexibility of case is common. For example, the writers of Matthew and Luke both relate Jesus's parable of the wise man who built his house upon a rock. Both writers related the same speech, but they used different cases for the object of akouo. Matthew used the accusative and Luke used the genitive.