If Seastone negates Haki, it's opposite would be a wellspring of Haki
But sea stone does not negate Haki specifically, that just a symptom, it negates the strenght of devil fruit users and their abilities which impacts their ability to use haki.
For the rest I'm sorry but you are making shortcuts where I can't follow.
Haki was always implicitely explained as the manifestation of a strong will power and Electro well... its simply an romanced extrapolation of the physical act of friction with fur. I think its not that deep, at least if we don't really want to explain this power.. because if we want to explain it.. then it can be explained quite easily without using the concept of light ( well not really at least) and it ties back to something I've been saying for a while now.
You see, in the world of One Piece, there are a few power and manifestation that - even for for this world - are quite bizarre. Those are :
- The Klabautermann : Merry
- Electro
- Some weird prophetic abilities (without devil fruits)
- The Diablo/Ifrit Jambe of Sanji
- The Fishman Karate
If you don't want to go deep, you could simply explained that those are the romanticized extrapolation of the nature of the characters, for example, Electro could simply be the romanticized result of the friction of the fur and fishman karate the romanticized fact that Fishmen are so familiar with water that they can bend it. But we could also take the road of a real explanation. And for that we don't need to search for long. It can be explained in one word:
Nika
You see, it has been established that devil fruit users when awakened can influence their environment. But Nika is something even more powerful, it does not only influence the environment, it can influence reality itself and as we have seen already, the reality of others:
We also know that the reality bending ability of the fruit had an influence on the reality of Luffy long before Gear 5
So.. let's sum up:
- Nika can influence the environment
- Nika can influence is own reality
- Nika can influence the reality of others
- Nika can influence reality even without awakening
Notice that we are talking here about:
- Fishmen
- Minks
- Strawhats
In others words we are talking about people who most likely had a long exposure with Joy Boy AND with Luffy.
So here is my hypothesis:
The influence of Nika CREATED all those powers or entities.
- The exposure to Joy boy allowed the Mink and Fishmen to developp superhuman abilities
- The exposure to Luffy allowed Sanji to developp diable Jambe
- The exposure to Luffy allowed Merry to manifest into reality (my guess is that a Klabautermann appeared before with Joy Boy)
So, no need to search for the light to explain Sulong or Electro. The simple exposure to Joy Boy could have triggered the manifestation of those powers.
But that's of course if we want to explain those phenomenons. I don't think its necessary.