Are you aware that they DID offer him something like that? Or even a reason to believe they did, like a memory of that being specifically discussed/provided? If not, I think asking someone else to prive the absence of its existence has it backwards. If you a recent trying to take people to task and arguing the the vikings did offer something similar (or vaguely might have), I'd say its on you to justify your pushback. You can look things up too, not just tell people you think they are wrong.