Nobody asked for it, but here's my $.02. Fair warning: if you have a phobia to religious stuff, just skip the next paragraph.
If your conscience can live with the consequences of keeping the phone you purchased, then keep it. But it is on your conscience/soul not only your consequences, but also the consequences for all involved (i.e. reprimands, etc. for BB employees, etc), and you will answer on the day of your judgement by your God.
IANAL, but I don't know that VZW can legally block a device that can function just fine on their network. Look for the Carterfone decision in which the US Supreme Court ruled that any device that will not cause harm to the telecommunications network must be allowed to be connected to said netwoiork. The fact that the phone has already passed through the FCC is enough (to me at least) to show that it will not cause harm to the network and other devices that use it (based on reading the little FCC approval sticker/disclaimer that comes with electronics). After a quick reading of the
Carterfone article on Wikipedia, it doesn't appear that anyone has actually taken any cellular provider to the SCOTUS trying to apply that decision though, so it would be (in theory) new legal territory. Also network neutrality principles may apply if it's using certain spectrum which have special neutrality requirements attached as condition of the sale.
I could also conceivably see a charge of receiving stolen property if somewhere in the contract between BB and VZW it says that the product is property of VZW until the phone is released to the public for sale and is only placed in a BB store for safe keeping/expedience on release day. At that point BB technically sold you a product that wasn't theirs to sell.
Again, I am NOT a lawyer (and I don't play one on TV), and I didn't stay at a Holiday Inn Express last night. I'm just a humble engineer who likes reading about technology and tech history and theorizing...