There are demon worshipping halflings down there that are the Golarian version of the classic "pygmy cannibals" - tusks totally goes with a character concept of a pygmy cannibal from the jungle.
So, neither illegal, nor cheese, nor even silly - just change the fluff on the trait from 'adopted by half orcs' to 'born of the kaava lands' and you're good to go.
I like it! Not cheesy at all really. Reminds me of those feral halflings from 2E Dark Sun set.
.
..
...
....
.....
Aww..
..a real pain-in-the knee.