Boy we’d better go check on Princess Anna’s corpse or something
While we’re at it we should probably get some legal proof from Hans that he was married to her and stuff
Also we should make sure that there aren’t any cousins who might have a stronger claim to Arendelle’s throne than this complete stranger
Yes, we should probably do these things
And this, folks, is WHY he buttered everyone up. So they wouldn’t question him about any of this. He’d presented as an honest and good man, so they’d had no reason to NOT believe him about the marriage vows or her death.