Who is this guy?
I've taken 1600 mg of Mag citrate + Mag carbonate in a day with no issue. That's not even including what I took in from foods.
Spreading dosing out to 4x/day also reduces the bowel issue, most people generally only will take their Mag 1 or 2x/day.
Albion is not the only company doing chelated minerals, so his post sounds more like a commercial to me.