So, I wish to clarify some misunderstood things.
First things first, why no Mahoraga against Conquest?
Reason: Because just like in JJK canon, in the four armed form Sukuna can't use the ten shadows - I didn't change that since I want the Megumi form to have its relevance, otherwise a guy like Sukuna who loves strength will never transform back.
Now, the big elephant in the room: The Compound Poison.
I already around 30 Chapters ago established that Viltrumites were interested in the spiritual and magic and already stated since the very beginning of this fic that it is an AU.
The fact there are more surviving Viltrumites isn't just for the fun of it, its because there were those scientists who studied magic enough to be able to save themselves and others.
I really like Invincible and JJK, I wouldn't write pointless plots.
If I write or elude to something - like the fact Battle Beasts daggers were able to disrupt Sukuna's cursed energy - since Cursed Energy is formed from emotions a spiritual aspect - I already dropped the hint for something like this.
Now, it working in the future? No, Sukuna is too smart for that and has Mahoraga.
So yeah, hope that clarified everything and if there are questions do ask them.
Bye!