There's not "nothing" wrong with MSG. But msg is fine in moderation, just like salt, fat and sugar are all fine in moderation too

If there's anything wrong with MSG that isn't simply due to sodium intake, I think it's unknown to science (at least in the sense that there's no theory about it with any wide uptake). MSG is also intensively studied and has a very similar mechanistic story to aspartame.

Sure, but it feels like a silly distinction. The famous example is water, which fits those same criteria. Would we that that there's not "nothing" wrong with water?