So... what they discovered is that limiting diets reduce reproduction at the expense of lifespan?
Color me skeptical, but this is not exactly new. It's well known that limited diets reduce reproductive metabolism in favor of survival. After all, what good is reproduction if you don't live to do it.
Now, I'm not saying this is all bunk. I don't know. What I am saying is that all this really proves is that methionine is necessary for egg-laying and lifespan in Drosophila. That's a far stretch from saying that reducing methionine increases lifespan in well-fed humans. In fact, what TFA says is that there is a discrepancy in studies. In fact, TFA doesn't even mention tryptophan, so I don't know where the submitter got that.
Unfortunately, I can't access the Nature article right now. However, I'll definitely be taking a look at it tomorrow, because I am extremely skeptical of these claims.