The emptiness of Valheim makes me feel kinda sad sometimes, and finding some NPC's living their lives here too could be a great addition.
That said, I don't think Ulf is stupid. The third person talking seems stupid nowadays, but was common for nordic writing. He seems to be an undereducated person unable to transmit all his toughts in words because of the lack of it. Also Ulf seems to be a good hearted person, since his stones always provides helpful tips for newcomers. Lastly, he's an Odin's warrior testing his value, just like you.
I'd like to know he's now at Valhalla, after accomplishing the hard work of Odin. Seeing other stones around, he might be the only one.