Both?
Who cares who to blame? It's not going to make the update come any faster.
There's really not enough information to "blame" one over the other. Has Motorola just not gotten around to it? Did they complete the update but Verizon hasn't approved it yet? Did Verizon tell them to hold off? Did Motorola deliver the update with bugs that had to be fixed and they haven't finished it yet?
None of us know. And, again - wth does it matter?