Not quite.
- The lvl 15 row would have a special Draft node, whether you drafted Nami or not. Having Nami unlocked is all it takes to make the Draft node spawn.
- This node offers three choices as usual but one of them is always the Nami bikini card, bypassing rerolls and anti-duplicate. This means this node is slightly weaker than regular Draft nodes, it only offers two other random choices even after you have made the special upgrade permanent.
- As you unlock more characters, more of these nodes spawn. This helps offset how new characters dilute the drafting pool by giving more opportunities to find characters and cards. It also gives more opportunities to dodge normal battles and progress further.