I remember years ago, our own Necrosis (yousmokepole) mentioned the concept of certain amino acids competing with the transport of others, and thus should not be taken together. I don't recall any further elaboration, but #1 above explains it.
This is the first I've heard of glutamine's other sides; some of them pretty serious, too. As an OTC supplement, I doubt this will receive the proper research it deserves to determine its longterm safety - at least not anytime soon.
I briefly used glutamine years ago, noticed nothing, and discontinued.
Great abstract!