The main reason why power scaling is not done based on religious beliefs is the logic that there is no such thing as a character being at the same power level as the religious figure they represent, which I agree with. For example, let me give an example from one of my favorite series, Bakugan. The character Ashura represents both Ashura and Brahman (I think that's how his name is written). Now, I can't come out and say that
Ashura (Bakugan)'s tier should be 1-A, High 1-A, etc. A character that resembles them doesn't mean that he is at their level. Imagine someone saying
Sengoku High 1-A/Boundless just because Sengoku ate the fruit of transforming into Buddha. I don't think scaling should be done from the words Nirvana. If Nirvana in that series contains a context that can increase the character's tier, maybe, but writing it as nirvana in that case would be problematic. If he has another name, it would be more accurate to write it that way.
Are we going to accept
Bakugan Tier 0 with power scaling from each Nirvana emote? That would be ridiculous.
In the Demon Slayer manga, the character
Gyutaro says, "Give me back my sister, I will slaughter all the Gods and Buddhas for her if necessary." Now, like the troll scaling pages, are we going to say that Buddha should be High 1-A/Boundless? The line here is both disturbing and there is no such thing as Buddha in the character's universe being the same power as in Buddhism.
Just because the character Ainz in the Ruruoni Kenshin series said "I need a higher power than God and Buddha to achieve my goal", are we going to consider Ainz and characters like Kenshin, Shisiho and Sanoske who are scaled to him as High 1-A/Boundlesss?
In short, friends, I find it objectionable to scale power based on religious beliefs. Both because it would make people uncomfortable (I'm not Buddhist, but I think I would be uncomfortable if I saw the panel where Gyutaro said that on this wiki) and because why would the power of a religious figure or god be at the same or similar level as a fictional character with the same name?