@KamiKira00 in the beginning it would work because he is not his friend would try to stop him from getting stronger, but eventually the previous MC would have noticed cuz he is the first it jump into conclusion. Once he gets something in his head, things won't change.
If you think about it the author of the book (the new MC) never really developed the character in depth. He only made it so, it would substitute his fantasy into a more concrete thing instead of having him just in his mind. The MC was never meant to be a MC as the hero. If you would have left him be, he could have turn out into the villain. This is why in this world created by the god, the MC shows the same original MC, but if we look it from a different perspective other than the MC POV, he would be the villain.
With that in mind, the new MC aka the author would look like the real villain because he lied the original MC to harm him and the plot wouldn't have been good and the new MC wouldn't have time to continue upgrading. Remember he is supposed to be the ultimate OP by god's instructions because he will have to deal with everything that the MC went thru otherwise things won't start similar or according to what happened in the book.