Negris never thought that even the Star Body would be unable to withstand it.
The Star Body is not simply material; it's formed by the Black Crystal Bone infused with augmentative increments. To bend and crush it, all the body's increments must be consumed.
So, what bears the pressure of the Divine Star isn't the bone itself, but the increments. Yet, from the looks of it, the weight seems capable of bursting the Star Body directly.
Ange also realized he couldn't dive any deeper, so he stopped at this depth and mobilized all his increments.
Ange transformed from a Cold Star to a Time-Space Ancient Dragon, then from a Time-Space Ancient Dragon to a Star Skeleton. The Cold Star has a large amount of increments, but they can't directly enter the Star Body.
The transformed Star Body requires increments to be projected from elsewhere.
