In M+ their values are almost the same, the Scale prevents ~3k more damage in this scenario, and the TUF and Death Chance values align with that. - I would have expected Scale to, well, scale better in a M+ script. But then, armor also scales up, maybe even better than the Scale absorb shield.
Stoneheart: Not Available
Scale: Not Available
So really to me it’s all about “why is the death chance so weird in the raid tanking script”. And the answer might just be, weird timing/edge cases/boss mechanics, which would be totally fair.
This all comes from the tank community saying Scale is the best trinket in the game by a lot, and Stoneheart is the worst (or maybe slightly better than Bladedancer’s Armor Kit). Which, I don’t think is actually all that true, given what I’ve seen here. But Scale is certainly a burstier defensive option, which seems difficult to assign a value to numerically.