His aura still contained the bomb. His semblance is literally mentioned to be an extension of his aura. He would have to output a power equal to the bomb in order to fully contain it with his construct. If he had put all of his aura into himself instead of the construct, he would have lived. He died because he drained his own personal force field to do so, leaving him vulnerable. Also, he could output that level of power at any time without killing himself. He could theoretically bubble something with that amount of power and still live.
What did I just say about his personal aura shields? They were lowered due to him using his semblance. It is something very consistent through the series. The more of your semblance you use, the more your own personal aura field is lowered. And, again, Vine’s semblance is literally an extension of his aura.
…Semblances have different properties than your base Aura. Hell semblances can AFFECT your aura. Jaune can literally use his semblance to refresh his own Aura. What are you talking about?
Semblances consume Aura to use but that process does not have to be 1:1. The max durability of your semblance and the amount of aura you HAVE are different. Your Aura can be cut through despite you still having Aura left.
So let’s apply that logic to attacks.
If you have a limit to the amount you can put into defense. Then you logically have a limit to the amount of energy you can put into your offense.
Physical amplification with Aura has never been explored in the manner you’re suggesting, so to make the wild assumption that feats performed via Semblances, which can operate outside of the normal limitations of the Aura’s damage threshold, can be performed while the base body, is insane.
“There’s no time to make it out of the blast range. I’ve killed us all.”
Harriet literally says this when the timer pops up. She does not believe she can survive this blast. She does not believe ANYONE can survive this blast.
Why. The. Hell. Would. She. Survive. It.
His semblance, Aura Vines, is unique to HIM in its properties. Projecting aura is something anyone can do but the way HE does it is unique. That’s why it’s his semblance. No one else should scale to HIS feat of containing the blast.