Cosidering Cultivation alone already encompasses Thorns I have to disagree.
I'd be inclined to agree but Brandon has been quite clear the Unmade had no Bondsmith equivelent.
Bonding an Unmade in the Radiant sense might be possible, but Big spren aren't always bondable, see Cusichesh.
there is something else required.
However, Yelig-nar forms a bond, and likely so do the others, I'm guessing we've seen at least some of the ways they work out