On Tuesday, Apple referred to federal court rules that prevent a non-party from making the statement it filed, in district court. If the court fails to reject Verizon's brief, Apple wants until October 6th to respond so that it can continue to work on the coming October 13th hearing on a possible ban of certain Samsung devices. Apple says that Verizon hadn't asked for its consent to produce its brief until the day that it was filed, not giving the former time to find evidence that might force the court to dismiss it.
Considering that Verizon gets much of its sales from Apple products in addition to Samsung devices, Verizon might have counted on Apple to attempt to block its amicus brief. The carrier might have just wanted to make a public show of supporting Samsung and Google. If Apple does win the case, Verizon will lose some business although speculation is that Samsung already has some new high-end Android devices, including the much anticipated Google Nexus Prime, coming as soon as early November.
source: FossPatents via Electronista (1), (2)