I suspect you're right, but I'm curious on if the math works out on that 'jewel slots transform damage into fire damage' node.
For instance, the bleed nodes near Duelist are in range. Does that mean it would transform those from '15% damage over time multiplier for bleeding' into ignite/burning damage? Would it make the other line in that node into Fire damage as well? There's also those notables near Iron Will that are phys that could be transformed into Fire for pretty good effect. Does it also do this for cluster notables? Those are 'non-unique' jewels, after all. That might be spicy somehow.
I'm not saying that's enough to save Chieftain for a slam->ignite build but... .. maybe? The only other thing I can think of is if there's enough suffixes saved on gear from the 2 resistance ascendancy nodes to make it good. Like, stack nothing but fire res, get the Formless Flame to stack armor for defense, ????, PROFIT! Or more seriously, replica dreamfeather for a non-slam build. I think the Tawhoa node being a prerequisite kills the 7 link node and makes it pure bait.
Honestly I think you could do some kind of fire conversion slam -> stun build now with some of the new passives and masteries and supports. Ironically I think it would work better on Zerker or Jugg or even Inquis now than Chieftain, which is just wrong.