But then why make the phones "unlockable" and advertise that they are if your gonna set limits like that. Overall even without the update I'm starting to realize how much further ahead my Samsung phone is then my iPhone was
I can't answer that, I've never dealt with unlocked phones. But I wouldn't put it past any company to make sure that if you are using one of their phones, but not using their network, to deny you updates via their network. These places make almost next to nothing on these phones nowadays, and they used to practically give them away with contracts. They want the services because that is where the money is, and if they aren't getting any money from you, they likely aren't going to give you anything in return.
If you know anyone who uses verizon it might be just easier to borrow their sim card to get the update and then swap back. Now that the "rush" is over it would take no time to get it downloaded and installed and it wouldn't affect their account either other than verizon seeing that they briefly swapped phones. Thinking about it, the only issue I could see with that route is that the phone may want to download contacts from the card, but I can't think of any others. Or perhaps you could contact Samsung about the process of updating an unlocked phone.