tis can be qualified as teory
.. becuz : teh S was crossed and c has dot..(this make u kestion teh meaning and theorize answers..)..
1-if tatoo was done befor meeting whitebeard ..then this creat plothole...how do ace know whitebeard befor and why would he tatoo letter "E"..also he couldldve wrote W(white beard) instead of E(edward newgate)..
2-S crossed could mean sabo death ( sabo exist no more)..but sabo for ace will always be alive..i dont tink ACE would cross sabo becuz for ace sabo will always remain alive ...
now Sabo was second comender of revolutionary army...and ace was whitebeard's secoond division commander ...dont that increace teh chances of them knowing that teh other is still alive???...what if ace met sabo beforwhitebeard death and tells him "in case i die plz take care of luffy and eat teh mera mera no mi.."
3-what if teh "S" was pirate name given to gold roger?? ..like when u can marshal de tech "BLACK BEARD"...thus thus ace crossing S would make sence becuz ace denied his father roger..
To consider something as a theory the bare minimum is that there has to be something substantially that actually supports it. Otherwise any random thought can be considered a theory. Not only has this nonsenses nothing to fall back on, it doesn't even explain anything. Even in the hypothetical case it would be true, zero progress would be made. The value of this would be even less than zero as you're trying to explain something that doesn't require an explanation.
1) I just checked and as expected Ace already had that tattoo. Also, this isn't a plot hole. This unquestionable proves that this sorry excuse for a theory is not true. For this to be considered a plot hole this 'theory' should have been confirmed to be true. You completely flipped this upside down.
2) The crossed S is a reference to Sabo's jolly roger, which was two crossed bones with an S in the center. When Sabo left the Goa kingdom you could see his jolly roger on his ship. However, before he left he sent a letter to Luffy & Ace that contains his jolly roger. This letter arrived after he presumably died.
This is something we only learned during a flash-back, hundreds of chapters after Ace was introduced. Before that the crossed S was pretty much seen as a gag; that the one who created the tattoo accidentally used an 'S' instead of a 'C' and had to cross it out. Then we suddenly learn it's actually not a mistake at all, but an early reference to a character we didn't know existed. This in return underlined how close the bond was between Ace & Sabo.
Forcibly trying to see something else in the other letters just makes a complete mockery of this.
3) Roger was called Gold Roger instead of Gol D Roger by the WG. This is something he himself explicitly said. On top of that he was called the Pirate King by the world. So, there's that.
This nonsense was either created by someone who meant it as a gag or one of those persons who thinks that there are clues hidden in every single rock Oda draws and the he somehow is the only one who spotted it.