I will not disagree that you have quite a well developed physique (at least your legs and back are awesome…that’s all I’ve seen).
The point being that there are people out there that can develope AWESOME physiques while eating absolute junk. And just because eating McDonalds doesn’t hurt THEIR progress, this does not mean that it will not hurt others. I knew this kid in high school that had an awesome physique, yet he ate crap all the time. Does that mean I could get away with the same? No.
I’m not saying that you will see improved gains with leaving out nutrasweet. Is it possible? Sure. But just to say that it’s fine based on whether or not it has hurt your progress is not reliable information, given the example above.
But I would absolutely agree that something like nutrasweet is minute compared to far more important aspects of diet.