I see what you're saying. I'm about to make the jump from Verizon to Page Plus as well (with an iPhone 5 though), and just wondered if I need to unlock the international feature before making the jump. Just wanted to make sure I wasn't missing anything.
Starting with the iPhone 5 due to the spectrum purchase that Verizon did for LTE service, any Verizon LTE capable phone with GSM band support has to be carrier unlocked from the factory. With Page Plus (technically, the only Verizon MVNO that supports LTE currently), you can only activate your phone on a $30 or more a month plan and they're axing flashed phone support after January 15th next year. However, due to the SIM slot being carrier unlocked by default, you can also choose any AT&T or T-Mobile MVNO from the guide you like. Right now, the best "unlimited" deals currently are with P'tel.
The Verizon and Sprint 4S with Truphone thing is more an anomaly solution (not that Truphone can't be a good deal for some GSM users in general), but it does open up a GSM MVNO option for the device where they might otherwise be restricted to only the usual CDMA MVNO options of Page Plus, Selectel, Ecomobile and Ting (depending on the phone's carrier branding).
Sorry if you mentioned it but I'm having trouble finding... what model phone is the problematic one?
Given the implied bits, I'm about 99% certain they both own Verizon iPhone 4S handsets and I acted as such without any protest from Pooperman... but you're quite right, handset info has been implied, not expressly stated.