The UserCanAlterTags attribute is for dialogue tags, not talents.
The closest I've gotten to get this work is to create a custom origin that adds the Dwarf_Sturdy tag, but the problem with a custom origin is that the dialog tags are locked, which is why I wanted to unlock them. But setting that value to 1 causes the origin to no longer show up in the character creator.
Though now that I actually try to create a character from that origin, the game doesn't start correctly. I am brought a shrine somewhere in a forest and have no character.
It just doesn't seem like the "Larian Guides" over at the Wiki were tested at all. Following them to the letter, not a single one has worked so far.