In fact, even Arcana, who could recover from partial source destruction by using the light of restoration, described her soon-to-happen complete source destruction as a salvation for herself:
Hwat? Nah, bro is tripping. Levingilma literally has high-godly regen neg
Anahem: Am I a joke to you?
So order makes that ruIe as a safety measure to make sure nothing happens to it, simpIe as that. Thats the simpIe scenario one can deduce from the why does that ruIe exist?
Headcanon. Where's your evidence?
Naphta literally self destructs because of her order
Cracks ran along the Goddess of the Future’s body as she began to break down. No matter how much she restricted the world, the only future in store for one facing me was destruction. That future was fast approaching Naphta.
Gods couldn’t defy order. Naphta had kept her eyes closed to avoid seeing this result.
Please re-read again. He just says it's because of the sword, but Nosgalia says they can't destroy it because the world would fall apart, then he gets angry because Anos controls the goddess's power (Negation his regeneration). Plus the incredible lack of context there is.
Also, why are they so sure that Nostalgia can fully return after its destruction, if Nosgalia himself got angry that Anos could control the power of the goddess (Negation his regeneration). He didn't even know that he could control her power anymore. So it's strange that they keep claiming that she regenerates even if her source is completely destroyed.
Reading comprehension just keeps leaving the chat huh? Nosgalia is surprised that he mastered the power not control it. Previousy all Anos could do was fully destroy, now he can break them just enough that they can't do shit anymore.
The scan you gave says it reduced the undestroyabIe god to nothingness, which just means it negated the fact that the the source of gods is infinite and thus cannot be reduced to nothingness, but the mauve eyes did so, it does not say that it was the reason they could not regenerate.
Three things make Gods undestroyable. Immortality, Regeneration and Invulnerability.
Astral, at this point I'm sure you're a child somewhere between 13-17 yrs of age give or take 2 years. This fixation on self-destruction that has nothing to do with anything here but for the sake of understanding and since it's Christmas, I'll humor you.
Self-destruction not being an option for the Gods for one is not referring to your fixation of blowing oneself up cause that's a stupid idea, it is referring to self-harm. Anos meant Nosgalia will not choose self harm in order to spite him.
Gods are orderly beings and they live their life according to the whims of their order. They live and die according to it, they cannot defy it and the same applies to spirits. Spirits live and die according to their rumors and lore. The way a god and spirit live their life is dependent on order and rumors respectively.
Deidrich seeking power wanted to become a proxy so he could overturn a prophecy but should he have become a god, he would be unable to overturn it since they cannot go against order.
Militia after creating Ennesuone which was an act that contradicted order and she could no longer cross Anos Beno Ievun because her order forced her to remain in the mortal world and she couldn't resist it. Militia normally can resist her order and go against it but creating Ennesuone weakened her.
Avernyu never wished to continuously destroy and cause death but because she was unable to go against her order, the sun of destruction continued to wreak havoc for millions of years until Anos showed up.
Speaking of self destruction, Anderk the Goddess of abortion killed herself (self harm) as a means to stop Ennesuone from being born and Anahem the God of death literally self destructed to escape Wenzel bindings. Eguz De Raphan the keepers of destruction would literally burn themselves under Sargeldonave and throw their flaming bodies against any intruders attempting to disrupt Sargeldonave
Gods exist for the purpose of maintaining order and harming themselves will literally disrupt it which is why it isn't an option for them. It's not some headcanon of a rule as you're insinuating if it were, none of the examples I gave above will even be possible.
I'd send scans but this is the limit I'm unwilling to cross in attempt to humor you. If you want to know more, feel free to go read vol 9, 10